The Number 10

What ten actually means across traditions

The Pythagorean decad, the ten sefirot of Sefer Yetzirah and the “ten words” of Sinai are all attested in the primary texts, and two ancient texts, Sefer Yetzirah and the Peripatetic Problemata, bring the ten fingers into the discussion of why the count is ten.

This page collects every attestation of 10 documented on this site — 4 entries drawn from 3 traditions — each with the source you would use to check it and the evidence grade it carries. The table is generated directly from the published dataset, so it cannot disagree with it.

Attestations of 10

Sorted by tradition. A grade of verified means the tradition demonstrably says this — not that the claim is true about the world.

Mathematical properties of 10

Computed, not asserted. These are the properties any numerological reading has to work with, and often the ones that explain a number’s practical popularity.

Why ten: what the primary texts say

The Problemata, a Peripatetic collection transmitted under Aristotle’s name but, in its translator’s judgement, not his own work, asks (XV.3, Bekker 910b) “Why do all men, barbarians and Greeks alike, count up to 10 and not up to any other number”. It offers five answers, all as questions and without choosing between them: ten is a “perfect number”; one, two, three and four make ten; the bodies that move in the heavens are nine; four cubic numbers arise “in ten proportions”; or “because all men have ten fingers” and count everything else with them as with counters. It also records an exception: one Thracian people counted only to four. On this site’s reading, the fingers are the only one of the five answers that explains the count without first treating ten as special: the others appeal to properties of numbers, to Pythagorean doctrine or to the number of the heavenly bodies.

Aristotle reports the Pythagorean reasoning running the other way (Metaphysics A.5, 986a8–12): “since the decad is considered to be a complete thing and to comprise the whole essential nature of the numerical system, they assert that the bodies which revolve in the heavens are ten; and there being only nine that are visible, they make the ‘antichthon’ the tenth.” The counter-earth was added to the sky because the number required it, and Aristotle presents it in exactly those terms. The same chapter credits some Pythagoreans with a table of ten pairs of opposites, from limit and unlimited to square and oblong (986a22–26).

Sefer Yetzirah sets “ten sefirot belimah” beside twenty-two letters (1:2), compares them to “the count of ten fingers, five against five” (1:3) and insists on the number: “ten and not nine, ten and not eleven” (1:4). The translator of Sefaria’s community translation notes that sefirot is formed from the verb safar, “to count”, reads it on one level as the ten digits of decimal counting, and cautions that the book need not give the ten sefirot the meaning later Kabbalah gave them.

The Hebrew Bible calls the Sinai commandments aseret ha-devarim, “the ten words” (Exodus 34:28; Deuteronomy 4:13; 10:4). The count is given; the division is not, and traditions draw it differently. The Mekhilta of Rabbi Ishmael (Bachodesh 8) records a dispute: Rabbi Hanina ben Gamliel holds that five were written on each tablet, with “I am the LORD your God” first, opposite “You shall not kill”, while the sages say all ten were written on each tablet. The Catechism of the Catholic Church (§2066) states that “the division and numbering of the Commandments have varied in the course of history”: it follows Augustine’s division, which is also that of the Lutheran confessions, while the Orthodox Churches and Reformed communities follow a division worked out by the Greek Fathers. Luther’s Small Catechism, accordingly, counts “Thou shalt have no other gods” as the first commandment and splits the coveting clause into the ninth and tenth.

What the evidence supports

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Sources

Where each claim in the overview, context and verdict can be checked. Primary texts first, then reference works.

• Aristotle, Metaphysics A.5, 986a8–12 and 986a22–26: Greek text ed. W. D. Ross (Oxford, 1924) and English translation by Hugh Tredennick (Loeb, 1933), Perseus Digital Library.
• [Aristotle], Problemata XV.3 (Bekker 910b), translated by E. S. Forster, The Works of Aristotle, vol. VII (Oxford, 1927), with Forster’s preface on authorship, Internet Archive; Greek text (Bekker) on Greek Wikisource.
• Sefer Yetzirah 1:2–1:4, Hebrew text (Warsaw, 1884) with the Sefaria Community Translation and its notes, Sefaria; the Gra version, translated by Aryeh Kaplan, Sefaria.
• Exodus 34:28 (Sefaria, Mechon Mamre), Deuteronomy 4:13 (Sefaria, Mechon Mamre) and 10:4 (Sefaria, Mechon Mamre), Masoretic text.
• Mekhilta de-Rabbi Yishmael, Tractate Bachodesh 8, Sefaria.
• Catechism of the Catholic Church, §2066, vatican.va.
• Martin Luther, Small Catechism, “The Ten Commandments”, Book of Concord.
• Carl Huffman, “Pythagoreanism” (plato.stanford.edu) and “Philolaus” (plato.stanford.edu), Stanford Encyclopedia of Philosophy (both revised 2024) — on the decad as the perfect number, the counter-earth and Philolaus, and on Zhmud’s view that the perfection of ten is a Platonic rather than a Pythagorean doctrine.

Other number hubs

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Cite this page

Formatted references for this page. The evidence grade is part of the claim — when quoting a graded statement, carry the grade with it.