9. The third is Τ, indicating the shape of the cross of the Lord.... The remaining two, the first and the last, Christ claims for himself. For he is himself the beginning, himself the end, saying: “I am α and ω,” for they pass into one another in turn, and alpha passes in regular succession to ω and again ω returns to alpha; in order that the Lord might show in himself that he was the way from the beginning to the end and from the end to the beginning. Chapter 4. On the Latin alphabet. 17. The nations gave the names of the letters in accordance with the sound in their own language, noting and distinguishing the sounds of the voice. After they had noted them, they gave them names and forms; and they made the forms in part at pleasure, in part according to the sound of the letters; as, for example, i and o, of which one has a slender stem, just as it has a thin sound; the sound of the other is gross (_pinguis_), just as its form is full. Chapter 5. On grammar. 1. Grammar is the science of speaking correctly, and is the source and foundation of literature.[179] This one of the disciplines was discovered next after the ordinary letters, so that those who have already learned the letters may learn by it the method of speaking correctly. Grammar took its name from letters, for the Greeks call letters γράμματα. [179] _Liberalium litterarum._ 4. The divisions of the grammatic art are enumerated by certain authorities as thirty; namely, eight parts of speech, the articulate voice, the letter, the syllable, metrical feet, accent, marks of punctuation, signs and abbreviations, orthography, analogy, etymology, glosses, synonyms, barbarisms, solecisms, [other] faults, metaplasms, schemata, tropes, prose, metres, fables, histories. Chapter 6. On the parts of speech. 1. Aristotle first taught two parts of speech, the noun and the verb. Then Donatus defined eight. But all revert to these two chief ones, that is, to the noun and the verb, which indicate the person and the act. The remainder are appendages, and trace their origin to these. 2. For the pronoun arises from the noun and performs its function, as _orator_, _ille_. The adverb arises from the noun, as _doctus_, _docte_. The participle from the noun and verb, as _lego_, _legens_. But the conjunction and preposition and interjection are included in those mentioned.[180] Many therefore have defined five parts because these are superfluous. [180] _In complexum istarum cadunt._ Chapter 21. On critical marks (_notae sententiarum_). 1. In addition there were certain marks in the writings of celebrated authors, which the ancients set in poems and histories to discriminate among the passages. A mark is a separate form placed like a letter, to indicate some judgment about a word, thought or verse. There are twenty-six marks used in annotating verses, which are enumerated below with their names.[181] [181] See _Etym._, 1, 21, 2–28. Chapter 22. On shorthand.