Isidore of Seville, Etymologiae 1.3
“Letters are so named as if from legiterae, because they show the road (iter) to readers (legentibus), or because they are repeated (iterentur) in reading (legendo). Latin and Greek letters seem to have arisen from Hebrew letters. For it is said that aleph was first spoken by the Hebrews, and then from a similar pronunciation alpha was drawn by the Greeks, which became A in the hands of the Romans. For a translator established the letter from the similar sound of the other language, so that we can understand Hebrew to have been the mother of all languages and letters. But the Hebrews use 22 letters in the books of the Old Testament; the Greeks however used 24. Coming in the middle of each of these two languages, the Romans have 23 letters. They say that Hebrew literature began with Moses: that of the Syrians and Chaldeans began with Abraham. For this reason, they agree with the Hebrew letters in number and sound, and differ only in the way they are written. The queen Isis, the daughter of Inachus, discovered and gave letters to the Egyptians when she came from Greece into Egypt. Among the Egyptians, however, the priests had one set of letters, and the mob had another. The sacerdotal letters were called hierai, and the common ones were called pendemoi. The Phoenicians first discovered the use of Greek letters, for which reason Lucan says,
‘If the story is to be believed, the Phoenicians first signified the voice to remain in rude figures…’
For this reason, the chapter headings of books are written in the Phoenician color (purple/red), because letters took their beginning with them. Cadmus, the son of Agenor, first brought seventeen letters from Phoenicia into Greece: Α.Β.Γ.Δ.Ε.Ζ.Ι.Κ.Λ.Μ.Ν.Ο.Π.Ρ.C.Τ.Φ. Palamedes added three to these in the Trojan war: Η.Χ.Ω. Subsequently, Simonides the lyric poet added three others: Ψ.Ξ.Θ. Pythagoras of Samos added Y after the example of human life: the lower line signifies the first part of life, since it is as yet unsettled and has given itself over neither to vices nor to virtues. The branch, which is above, begins in adolescence: the right part is hard but leads to happy life. The left part is easier, but leads down to ruin and death. About it, Persius writes,
‘And to you, where the letter has drawn down the Samian branches, on the right limit it showed the rising path.’
There are however five mystic letters among the Greeks. The first is Y, which signifies the human life, and about which we just spoke. The second is Θ, which signifies death. For judges used to place Θ next to the names of those whom they would afflict with punishment. Theta receives its name from death [apo tou thanatou]. This is why it has a dart in the middle of it, that is, the sign of death. About which we read,
‘O Theta, the letter far more unfortunate than the rest.’
Litterae autem dictae quasi legiterae, quod iter legentibus praestent, vel quod in legendo iterentur. Litterae Latinae et Graecae ab Hebraeis videntur exortae. Apud illos enim prius dictum est aleph, deinde ex simili enuntiatione apud Graecos tractum est alpha, inde apud Latinos A. Translator enim ex simili sono alterius linguae litteram condidit, ut nosse possimus linguam Hebraicam omnium linguarum et litterarum esse matrem. Sed Hebraei viginti duo elementa litterarum secundum Veteris Testamenti libros utuntur; Graeci vero viginti quattuor. Latini enim inter utramque linguam progredientes viginti tria elementa habent. Hebraeorum litteras a Lege coepisse per Moysen: Syrorum autem et Chaldaeorum per Abraham. Unde et cum Hebraeis et numero et sono concordant, solis characteribus discrepant. Aegyptiorum litteras Isis regina, Inachis filia, de Graecia veniens in Aegyptum, repperit et Aegyptiis tradidit. Apud Aegyptios autem alias habuisse litteras sacerdotes, alias vulgus; sacerdotales ἱερὰς, πανδήμους vulgares. Graecarum litterarum usum primi Phoenices invenerunt; unde et Lucanus (3, 220):
Phoenices primi, famae si creditur, ausi
mansuram rudibus vocem signare figuris.
Hinc est quod et Phoeniceo colore librorum capita scribuntur, quia ab ipsis litterae initium habuerunt. Cadmus Agenoris filius Graecas litteras a Phoenice in Graeciam decem et septem primus attulit; Α.Β.Γ.Δ.Ε.Ζ.Ι.Κ.Λ.Μ.Ν.Ο.Π.Ρ.C.Τ.Φ. His Palamedes Troiano bello tres adiecit Η.Χ.Ω. Post quem Simonides Melicus tres alias adiecit Ψ.Ξ.Θ Υ litteram Pythagoras Samius ad exemplum vitae humanae primus formavit; cuius virgula subterior primam aetatem significat, incertam quippe et quae adhuc se nec vitiis nec virtutibus dedit. Bivium autem, quod superest, ab adolescentia incipit: cuius dextra pars ardua est, sed ad beatam vitam tendens: sinistra facilior, sed ad labem interitumque deducens. De qua sic Persius ait (3, 56):
Et tibi qua Samios deduxit littera ramos,
surgentem dextro monstravit limite callem.
Quinque autem esse apud Graecos mysticas litteras. Prima Υ, quae humanam vitam significat, de qua nunc diximus. Secunda Θ, quae mortem [significat]. Nam iudices eandem litteram Θ adponebant ad eorum nomina, quos supplicio afficiebant. Et dicitur Theta ἀπὸ τοῦ θανάτου, id est a morte. Unde et habet per medium telum, id est mortis signum. De qua quidam:
O multum ante alias infelix littera theta.