Where these came from
Twenty-three systems, ordered by the oldest thing that actually survives. Not what each tradition claims for itself — the object, the manuscript, the account book, with a date and a place. And then, for each, the far more recent moment when the version you have met was fixed, and by whom.
The chronology
20 of 23 systems have a defensible attestation date. The other 3 do not, and are listed after.
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c.1275 BCE
The Dream Symbols Part evidence, part tradition
Papyrus Chester Beatty III (P. BM EA 10683)
Deir el-Medina, Egypt · Hieratic Egyptian
A working scribe's dream manual, ruled in two columns: the dream on the left, the verdict on the right, each entry marked good or bad. It lists roughly 139 dreams. It belonged to the scribe Qenherkhepeshef, whose household kept it for at least two more generations — his widow's second husband and his son both added their names. On the back, someone copied out a poem about the Battle of Kadesh, which is how the papyrus is dated to the early reign of Ramesses II.
The version you have met: 1900 · Sigmund Freud, with the symbol dictionaries that followed him
3,175 years between the earliest artifact and the version now sold.
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c.800 BCE
The I Ching Traditional
The Zhou Yi, the core text of hexagram and line statements
The Zhou royal domain, north China · Old Chinese
Sixty-four hexagrams, each with a short judgement and six line statements. The language is terse, concrete and often agricultural or military — captured oxen, a wounded thigh, crossing a great water. There is almost no philosophy in it. It is a diviner's field manual, and it reads like one.
The version you have met: 1950 · Wilhelm, Baynes and Jung
2,750 years between the earliest artifact and the version now sold.
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c.500 BCE
The Nine-Year Cycle Traditional
The Pythagorean tradition as reported by later writers
Croton, Magna Graecia · Greek
Almost nothing first-hand. Pythagoras left no writings; what survives are reports by Aristotle, Iamblichus and Porphyry, written between two hundred and eight hundred years later. What they describe is a doctrine that number is the substance of things — which is a metaphysics, not a personality system.
The version you have met: 1908 · L. Dow Balliett, developed by Juno Jordan
2,408 years between the earliest artifact and the version now sold.
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c.450 BCE
The Five Elements Traditional
The fragments of Empedocles, On Nature
Akragas, Sicily · Greek
About 450 lines of hexameter verse, quoted by later authors. Empedocles calls them roots, not elements — fire, water, earth and air — and holds that everything is a mixture of the four, driven together by Love and apart by Strife. There are four. Not five.
The version you have met: 1888 · The Hermetic Order of the Golden Dawn, popularised through Wicca from the 1950s
2,338 years between the earliest artifact and the version now sold.
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c.400 BCE
The Twelve Signs Traditional
Babylonian zodiacal texts and the earliest horoscope tablets
Babylon · Akkadian, in cuneiform
The division of the ecliptic into twelve equal thirty-degree signs appears in Babylonian astronomical texts in the fifth century BCE. The earliest surviving individual horoscope is a cuneiform tablet dated to 410 BCE. Before that, the star catalogue MUL.APIN records constellations and calendar rules going back perhaps to 1000 BCE, but without the twelve equal signs.
The version you have met: 1930 · R. H. Naylor and the popular press; Alan Leo for the psychological turn
2,330 years between the earliest artifact and the version now sold.
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c.315 BCE
The Stones Traditional
Theophrastus, Peri Lithon (On Stones)
Athens · Greek
A short treatise by Aristotle's successor at the Lyceum, classifying about seventy stones and earths by origin, hardness, colour and behaviour in fire. It is a mineralogy, and a good one. It records some traded beliefs about powers, and is notably unimpressed by most of them.
The version you have met: 1985 · Katrina Raphaell, and the market her trilogy opened
2,300 years between the earliest artifact and the version now sold.
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c.300 BCE
Wood, Fire, Earth, Metal, Water Part evidence, part tradition
The wu xing doctrine as transmitted from Zou Yan
The state of Qi, north-east China · Old Chinese
Zou Yan (c. 305-240 BCE) is credited by the Han historian Sima Qian with systematising the five phases into cycles of generation and conquest and applying them to dynastic succession. His own writings are lost. The doctrine is fully present in the Huangdi Neijing, compiled between roughly the second century BCE and the second century CE.
The version you have met: 1958 · The People's Republic of China, Ministry of Health
2,258 years between the earliest artifact and the version now sold.
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c.200 BCE
The Three Doshas Part evidence, part tradition
The Charaka Samhita
Northern India · Sanskrit
A large medical compendium on internal medicine, redacted over centuries; the surviving recension is usually placed between the second century BCE and the second century CE, with a further redaction by Dridhabala around the fourth. Alongside it sits the Sushruta Samhita on surgery. Both are substantial clinical works, and both describe the three doshas as a physiological theory rather than a personality quiz.
The version you have met: 1991 · Deepak Chopra, Perfect Health, and the market it opened
2,191 years between the earliest artifact and the version now sold.
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c.100 BCE
Open the Book at Random Traditional
The Homeromanteion papyri
Greco-Roman Egypt · Greek
Papyrus fragments containing numbered lines of Homer arranged for use as an oracle: throw dice, take the number, read the line. Three copies survive. The practice is older than the papyri — the sortes are already a known Roman institution — but this is the earliest surviving apparatus for doing it.
The version you have met: Nobody. It has no modern systematiser, which is unusual in this series.
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c.150 CE
The Runes Traditional
The Vimose comb
Vimose bog, Funen, Denmark · Proto-Germanic, in Elder Futhark
A bone comb with a single word cut into it: harja. Either a personal name or the word for warrior, or possibly the word for comb. It is dated to around 160 CE and is the oldest inscription that is beyond dispute runic. The cutting is confident and mature, which is why philologists assume at least a century of prior use that has not survived.
The version you have met: 1982 · Ralph Blum
1,832 years between the earliest artifact and the version now sold.
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c.300 CE
The Arranged Room Part evidence, part tradition
The Zangshu, the Book of Burial, attributed to Guo Pu
China, Eastern Jin · Classical Chinese
A short treatise on siting graves so that qi accumulates rather than disperses, attributed to Guo Pu (276-324 CE). It gives the discipline its name — wind and water — and its founding idea: that the shape of land and the flow of air and water around a site determine what happens to what is placed there. It is about tombs. Houses come later.
The version you have met: 1983 · Lin Yun's Black Hat school, in English through Sarah Rossbach
1,683 years between the earliest artifact and the version now sold.
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c.350 CE
The Ogham Traditional
The orthostat ogham inscriptions of southern Ireland
Munster, Ireland, and south-west Wales · Primitive Irish
Roughly four hundred stone inscriptions, cut as notches across or beside the edge of an upright stone. Almost all of them are the same kind of text: a name in the genitive, a father's or ancestor's name, sometimes a tribe. They are boundary and memorial markers. The earliest are fourth century.
The version you have met: 1948 · Robert Graves
1,598 years between the earliest artifact and the version now sold.
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c.900 CE
The Seven Centres Traditional
The Kubjikamata Tantra and related Sanskrit tantric works
North India and Nepal · Sanskrit
Tantric manuals describing chakras as points for visualisation and ritual practice within a yogic body. The number varies by text and by lineage — four, five, six, seven, nine, twelve. The influential six-plus-one arrangement is fixed relatively late; the Sat-Cakra-Nirupana, the text most Western accounts ultimately depend on, was written in 1577.
The version you have met: 1977 · Christopher Hills, elaborated by Anodea Judith
1,077 years between the earliest artifact and the version now sold.
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c.1440 CE
The Tarot Traditional
The earliest references to carte da trionfi, and the Visconti-Sforza decks
Florence, Ferrara and Milan · Italian
A 1440 Florentine diary reference, an entry in the Duke of Ferrara's account book of 1442, and a set of hand-painted luxury decks made for the Visconti and Sforza courts of Milan. They are playing cards: a standard four-suit pack with a fifth suit of allegorical trumps added, for a trick-taking game in which the trumps beat the suits. That is what trionfi means.
The version you have met: 1910 · Pamela Colman Smith, under A. E. Waite's direction
470 years between the earliest artifact and the version now sold.
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1799
The Lenormand Traditional
Das Spiel der Hofnung (The Game of Hope)
Nuremberg · German
A boxed parlour game published by Johann Kaspar Hechtel in 1799: thirty-six numbered cards, each carrying a small symbol and a playing-card inset, laid out in a grid as a race track. Players moved counters along it by dice. Those thirty-six symbols — the Rider, the Clover, the Ship, the Coffin — are exactly the modern Lenormand deck.
The version you have met: 1846 · An anonymous German publisher, capitalising on a dead woman's fame
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1897
The Cycles Tested, and it failed
Wilhelm Fliess's periodicity papers, and later Der Ablauf des Lebens (1906)
Berlin · German
Fliess, a Berlin nose-and-throat specialist and Freud's closest correspondent for a decade, proposed that human life is governed by two cycles — 23 days male, 28 days female — and derived them by finding combinations of 23 and 28 that fitted dates in his patient records. Freud believed it for years. The arithmetic is the kind that can fit anything.
The version you have met: 1976 · Bernard Gittelson and the pocket-calculator industry
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1943
The Sixteen Types Widely used, weakly validated
The first Myers-Briggs Type Indicator, Form A
Swarthmore, Pennsylvania · English
A questionnaire written by Katharine Cook Briggs and her daughter Isabel Briggs Myers, neither of whom had formal training in psychology or psychometrics. Myers learned test construction from a personnel manager at a Philadelphia bank. The instrument was built to help women entering wartime industry find suitable work, which is a decent motive and an unusual origin for a psychological test.
The version you have met: 1975 · Consulting Psychologists Press, now The Myers-Briggs Company
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1958
Two of You Part evidence, part tradition
Bowlby, The Nature of the Child's Tie to His Mother
London, the Tavistock Clinic · English
A paper arguing that the infant's bond to a caregiver is a primary biological system rather than a by-product of feeding. It was heretical to both psychoanalysis and behaviourism at the time. Everything defensible in this volume descends from it; the parts of the volume that do not descend from it are marked.
The version you have met: 1998 · Relationship science, on two continuous dimensions
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1968
The Nine Types Widely used, weakly validated
Oscar Ichazo's protoanalysis teaching at the Arica School
Arica, Chile, and Santiago · Spanish, then English
Ichazo was the first person to map psychological types onto the nine-pointed figure. He taught nine ego fixations, each with a passion and a virtue, within a larger system he called protoanalysis. The figure itself he took from Gurdjieff; the personality content is his.
The version you have met: 1987 · Riso and Hudson, on Naranjo's profiles, on Ichazo's fixations
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1987
The Five Types No research behind it
Ra Uru Hu's account of an eight-day transmission on Ibiza
Ibiza, Spain · English
Alan Robert Krakower, born Montreal 1948, a former advertising man and magazine publisher living on Ibiza, reported that on the evening of 3 January 1987 he was contacted by a Voice, and that over the following eight days and nights, barely sleeping, he wrote down the system. He took the name Ra Uru Hu and taught it until his death in 2011. The account is his and has never been corroborated or contested by any other party, because there was no other party.
The version you have met: 1987 · Ra Uru Hu (Alan Krakower)
The three that cannot be dated
No honest date exists for these, and inventing one would be worse than leaving the column empty.
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contemporary
The Eight Phases Part evidence, part tradition
No single origin; lunar calendars are among the oldest human records
Everywhere · Every language
Tally marks on bone from the Upper Palaeolithic have been argued to be lunar counts, though the interpretation is disputed. What is certain is that lunar calendars predate solar ones nearly everywhere, because the moon is the only obvious clock in the sky that changes visibly every night. The eight-phase scheme used in this volume is a modern convenience, not an ancient standard.
The version you have met: 1980 · Contemporary neopagan and wellness practice
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contemporary
The Pattern Atlas Evidence-informed
The cognitive and clinical literature of the last sixty years
Philadelphia, Oxford, and the clinical research tradition generally · English
This volume has no tradition behind it and does not pretend to one. Its twelve loops — perfectionism, comparison, people-pleasing, avoidance, the burnout spiral, the freeze response and the rest — are drawn from cognitive therapy, attachment research, and the stress and trauma literature. Where a loop has a named originator, the volume names them.
The version you have met: 1967 · Beck, and six decades of clinical trial since
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contemporary
Ten Practices Evidence-informed
The intervention literature: trials, not traditions
Clinical and social psychology, internationally · English
Ten small practices — expressive writing, gratitude, the body scan, behavioural activation, sleep regularity, walking, naming an emotion, a values check, a single deliberate contact, and doing one thing badly on purpose — each chosen because it has been tested and each carrying its own effect size in the text. Nothing is here because it is traditional.
The version you have met: 2015 · Post-replication intervention science
Younger than you think
The eight most recent moments at which a system in this series took the form now sold.
| Fixed | System | By whom |
|---|---|---|
| 2015 | Ten Practices | Post-replication intervention science |
| 1998 | Two of You | Relationship science, on two continuous dimensions |
| 1991 | The Three Doshas | Deepak Chopra, Perfect Health, and the market it opened |
| 1987 | The Nine Types | Riso and Hudson, on Naranjo's profiles, on Ichazo's fixations |
| 1987 | The Five Types | Ra Uru Hu (Alan Krakower) |
| 1985 | The Stones | Katrina Raphaell, and the market her trilogy opened |
| 1983 | The Arranged Room | Lin Yun's Black Hat school, in English through Sarah Rossbach |
| 1982 | The Runes | Ralph Blum |
47 things you have probably been told
Each of these is a claim in wide circulation, stated the way it is usually stated, followed by what the record shows. They are printed in the books as well, in the front matter, before the reader reaches a single entry.
Dream dictionaries record ancient universal symbolism.
They record a twentieth-century publishing format. The oldest surviving dream book does contain a fixed list, but its verdicts are omens about the world, not statements about the dreamer's psyche, and Artemidorus was already arguing against fixed meanings in the second century.
Papyrus Chester Beatty III; Artemidorus, Oneirocritica, c. 150 CE
Everyone dreams in symbols that mean the same thing.
Content analysis of large dream collections finds strong regularities in what people dream about — falling, being chased, teeth, being unprepared — and no regularity at all in what those dreams correspond to in a given dreamer's life.
Hall and Van de Castle content-analysis corpus, 1966 onward
The I Ching is five thousand years old and was written by Fu Xi.
Fu Xi is a mythological culture hero. The text is Zhou, not legendary, and the philosophical layer everyone quotes is six hundred years younger than the oracle it is attached to.
Shaughnessy, The Composition of the Zhouyi, 1983
Confucius wrote the Ten Wings.
Attributed to him traditionally; assigned to his school across several generations by every modern textual analysis, including comparison with the Mawangdui manuscripts.
Mawangdui silk texts, excavated 1973
Pythagoras invented numerology.
Pythagoras held that number underlies reality. He is not recorded as having reduced anybody's name to a digit, and the earliest source for his views is Aristotle, writing after his death.
Aristotle, Metaphysics A.5
The nine-year cycle is ancient.
It appears in print in the early twentieth century. No classical, Hebrew or Arabic source describes it.
Balliett, Philosophy of Numbers, 1908
The five elements are ancient Greek.
The four are. Aristotle's fifth was aether, a substance he placed in the heavens and denied to the sublunary world; equating it with spirit is a Renaissance and then a modern move.
Aristotle, On the Heavens I.2-3
The Greek and Chinese five elements are the same system.
They are not related and do not even have the same members. Wu xing is Wood, Fire, Earth, Metal and Water, and it describes cycles of generation and control rather than substances. This series gives them separate volumes for that reason.
See the five-elements-tcm volume
Astrology is five thousand years old.
Sky omens are. The twelve-sign zodiac is about 2,400 years old, the natal chart with houses and aspects is Hellenistic, and the sun-sign column dates from 1930.
Rochberg, The Heavenly Writing, 2004
Astrologers do not know about precession.
Ptolemy discusses it in the second century. Western astrology uses a tropical zodiac anchored to the equinox and knows perfectly well that it no longer lines up with the constellations; whether that is defensible is a separate argument from whether it is known.
Ptolemy, Tetrabiblos and Almagest
Crystal healing is an ancient practice.
Stones have been valued, worn and credited with virtues for millennia. The specific modern system of chakra placement, programming and grids was invented by one author in 1985 and has no ancient counterpart.
Raphaell, Crystal Enlightenment, 1985
Quartz is used in electronics, therefore it has energetic effects.
Quartz is piezoelectric: mechanical stress produces a measurable voltage across the crystal. That effect requires cutting to a specific orientation and physical compression, produces microvolts, and has no route to physiology. The word energy is doing two entirely different jobs in that sentence.
Curie and Curie, 1880, on piezoelectricity
Wood, Fire, Earth, Metal, Water
TCM is an unbroken five-thousand-year tradition.
The materials are ancient and genuinely continuous. The syllabus is not: it was assembled in the 1950s from lineages that disagreed with each other, and the disagreements were resolved administratively.
Taylor, Chinese Medicine in Early Communist China, 2005
Wood, Fire, Earth, Metal, Water
Wu xing means the same as the Greek four elements.
Wu xing are phases, not substances — five positions in a cycle of generation and control. Wood generates Fire; there is no Greek equivalent of that sentence.
Sivin, Traditional Medicine in Contemporary China, 1987
Your dosha is a fixed personality type.
Classical texts distinguish prakriti, the constitution you are born with, from vikriti, the current imbalance. Almost all popular material collapses the two, which is why the quiz result changes when you are tired.
Charaka Samhita, Vimanasthana 8
Ayurveda is the world's oldest medical system.
Egyptian and Mesopotamian medical papyri and tablets are older as surviving documents. Ayurveda has the strongest claim to being the oldest medical system still in continuous large-scale clinical use, which is a different and more interesting claim.
Edwin Smith and Ebers papyri, c. -1600
Bibliomancy is a Christian practice.
It is pre-Christian, was practised on Homer and Virgil first, and was condemned by church councils more often than it was endorsed.
Council of Vannes, 465; Council of Agde, 506
The passage that comes up is chosen for you.
The passage is chosen by the physics of a book's spine, which opens preferentially where it has been opened before. That is a real and documented bias, and it is not the kind anyone claims.
Observable in any well-used book
The runes were an oracle used by the Vikings.
They were an alphabet. Roughly six thousand runic inscriptions survive and they are names, memorials, ownership marks, prayers and graffiti. No surviving inscription is a divinatory reading.
Page, An Introduction to English Runes, 1999
The blank rune is Odin's rune, the rune of the unknowable.
It was introduced by Ralph Blum in 1982. There are twenty-four Elder Futhark characters and none of them is blank.
Blum, The Book of Runes, 1982
The wealth corner is ancient Chinese practice.
Orienting the bagua to the front door instead of to magnetic south is a Black Hat innovation from the 1980s. Classical practice requires a compass reading and a birth date.
Bruun, An Introduction to Feng Shui, 2008
Feng shui is about decorating your home.
For most of its history it was primarily about where to bury the dead, and secondarily about where to site a settlement. Interior arrangement is a late and minor application.
Guo Pu, Zangshu
The Celtic tree calendar is ancient druidic knowledge.
It first appears in The White Goddess in 1948. There is no historical Celtic calendar of thirteen tree months in any source.
Graves, The White Goddess, 1948; and the Celticist response to it
Ogham was a secret druid script.
It was a script for cutting names into stone, closely modelled on Latin grammatical categories, most likely devised by people who knew Latin well. Its surviving use is public and territorial, not secret.
McManus, A Guide to Ogam, 1991
The seven rainbow chakras are ancient Vedic knowledge.
The Vedas do not describe them. The tantric sources are medieval, disagree on how many there are, and assign colours that are not a spectrum. The rainbow ordering dates from 1977.
Hills, Nuclear Evolution, 1977; Woodroffe, The Serpent Power, 1919
Each chakra corresponds to an endocrine gland.
The gland correspondences are Leadbeater's, offered in 1927 as clairvoyant observation. They are not in any Sanskrit source and were not derived from anatomy.
Leadbeater, The Chakras, 1927
Tarot comes from ancient Egypt.
Invented by Court de Gebelin in 1781 and repeated ever since. The cards are fifteenth-century Italian, the trump sequence is drawn from thoroughly-documented Italian allegorical imagery, and there is no Egyptian connection of any kind.
Decker, Depaulis and Dummett, A Wicked Pack of Cards, 1996
Tarot was always used for divination.
There is no record of a divinatory tarot reading before the late eighteenth century, and a great deal of record of tarot card games throughout that period.
Dummett, The Game of Tarot, 1980
The Major Arcana encode a secret initiatory tradition.
The trump sequence's imagery — the Pope, the Emperor, Death, the Wheel of Fortune, the Last Judgement — is standard late-medieval Italian moral allegory, legible to anyone who had been inside a church.
Moakley, The Tarot Cards Painted by Bonifacio Bembo, 1966
Marie Anne Lenormand created this deck.
She died in 1843. The cards were published as a parlour game in 1799 by Johann Kaspar Hechtel and were attached to her name around 1846 to sell them.
Hechtel, Das Spiel der Hofnung, Nuremberg 1799
Lenormand is a simplified tarot.
It is not related to tarot and does not work like it. Lenormand cards have narrow literal meanings and are read in combination, closer to a sentence than to a symbol. Reading one card deeply, tarot-style, is the standard beginner's error.
Standard Lenormand practice
Biorhythms are based on real biological cycles.
Real biological rhythms exist and are well documented — circadian, ultradian, menstrual, seasonal. None of them has a fixed period counted from date of birth, which is what biorhythm theory requires and what makes it testable.
Hines, Psychological Reports 83, 1998
Biorhythm was never properly investigated.
It was investigated more thoroughly than almost anything else in this series. Hines reviewed 134 studies. That is why this volume is rated disconfirmed rather than untested.
Hines, Comprehensive Review of Biorhythm Theory, 1998
The MBTI is based on Jung's research.
It is based on Jung's book, which was itself based on his clinical impressions rather than on data. The judging-perceiving axis is not Jung's at all; Briggs and Myers added it.
Jung, Psychological Types, 1921
Your type is fixed for life.
Around half of people who retake the instrument after five weeks receive a different four-letter type. The manual's own framing of type as innate and lifelong is not supported by its own retest data.
Howes and Carskadon, 1979
You have one attachment style.
Attachment is measured dimensionally and varies by relationship. A person can be secure with one partner and anxious with another, and the scores move with circumstance.
Brennan, Clark and Shaver, 1998; Fraley, 2002
Everyone has a primary love language.
The research finds people value all five, that the five overlap heavily, and that matching partners on them does not reliably predict satisfaction. All three of the book's central assumptions fail.
Impett, Park and Muise, Current Directions, 2024
The Enneagram comes from the desert fathers, or from Sufism.
No patristic or Sufi source contains it. Ichazo made various claims about his sources over the years; the personality system appears in the historical record in 1968 and not before.
Hook et al., Journal of Clinical Psychology, 2021
Gurdjieff taught the nine types.
Gurdjieff taught the figure as a process diagram. Every surviving account from his students describes it that way, and none mentions personality types.
Ouspensky, In Search of the Miraculous, 1949
Human Design synthesises ancient wisdom traditions.
It borrows vocabulary from four of them. None of the four contains anything resembling the bodygraph, the types, the authorities or the profile lines, and no practitioner of any of the four would recognise the result.
Comparison with the I Ching, tantric and kabbalistic sources
The system is based on neutrino physics.
Neutrinos are real and pass through matter constantly. They interact so weakly that detecting them requires instruments the size of buildings; they carry no information about a birth moment and no mechanism has ever been proposed for how they would imprint one. The claim is decorative.
Standard particle physics
The moon affects us because we are mostly water.
Tides arise from the difference in the moon's pull across a body's width. Across a human body that difference is on the order of a ten-millionth of the gravitational effect of the building you are standing in. The Great Lakes barely tide; a person does not.
Standard gravitational physics
The full moon increases hospital admissions, crime and births.
Tested extensively and repeatedly. A meta-analysis of thirty-seven studies found lunar phase accounted for no more than one per cent of the variance in any of these.
Rotton and Kelly, Psychological Bulletin 97, 1985
Naming a pattern fixes it.
Recognition is necessary and nowhere near sufficient. The trial evidence supports structured practice over weeks; insight alone reliably changes very little.
The CBT outcome literature generally
These are personality traits.
They are processes, which is why they respond to practice. A trait is something you have; a loop is something you are doing, and the distinction is the reason this volume exists.
Nolen-Hoeksema on rumination as process
Gratitude journalling will make you significantly happier.
Effects are real, small, and largest in people who were low to begin with. Meta-analyses put them well below what the popular literature implies, and daily practice does not outperform weekly.
Davis et al., Journal of Counseling Psychology, 2016
These are ancient practices validated by modern science.
Some have contemplative ancestry and some are inventions of the research literature. Where a practice was tested in a form that differs from its traditional version, the volume says which version was tested.
Kabat-Zinn on the deliberate secularisation of MBSR
Questions
Why does this page exist?
Because every book in this category calls its subject ancient and almost none of them says which century, which object, or whose name is on it. The difference between a practice attested in 1275 BCE and a system published in 1982 is not a detail, and a reader who is not told cannot hold either one at the right distance.
Does a recent origin make a system worthless?
No, and this series is emphatic about it. The most recently invented system here is Human Design, from 1987, and its advice about how you spend energy is worth having. The most anciently attested is the Egyptian dream book, and a dream dictionary is still a dream dictionary. Age is not quality. It is provenance, and provenance is what you need in order to know what kind of confidence to hold.
Where do these dates come from?
Each is the date of a named surviving artifact — a papyrus, an inscription, an account book, a published title — not the date a tradition claims for itself. The sources are listed on each volume page and in each book's own front matter.
What is the gap figure?
The distance between the earliest surviving evidence of a system and the point at which the version now sold was actually fixed. Tarot's is the largest in the series: the cards are from the 1440s and the deck almost everyone owns was drawn in 1910.
Are the corrections meant to debunk these practices?
No. Every one of them is followed, in the book, by what survives the correction — and something always does. A practice can be younger than advertised, wrongly attributed, and still worth the evening. What it cannot be is misrepresented to you by the person selling it.