Etymologiae, Book I, chapters 20-21: De posituris to De notis sententiarum
Chapter XX. On punctuation Punctuation (positura) is a figure for distinguishing senses by clauses, phrases and periods, which, when set in its proper order, shows us the sense of the reading. Punctuations are so called either because they are marked by points set down (positis), or because there the voice is lowered for the interval of the pause. The Greeks call these theseis, the Latins positurae. The first punctuation is called the subdistinction; the same is also the comma. The next is the middle distinction; the same is the colon. The last is the distinction which closes the whole sentence; it is the period, of which, as we have said, the parts are the colon and the comma; their difference is shown by points set in different places. For where at the beginning of pronouncing the part is not yet full for the sense, and yet it is fitting to take breath, a comma is made, that is, a little portion of sense, and the point is set at the bottom of the letter; and it is called subdistinction, from the fact that it takes the point below, that is, at the bottom of the letter. Where, however, in what follows the sentence already gives a sense, but something still remains of the fullness of the sentence, a colon is made, and we mark the middle of the letter with a point; and we call it the middle distinction, because we put the point at the middle of the letter. Where, finally, by degrees in pronouncing we now make the full close of the sentence, a period is made, and we put the point at the top of the letter; and it is called distinction, that is, separation, because it has set apart an entire sentence. This holds among the orators. Among the poets, however, where in a verse a syllable remains after two feet, it is a comma, because there after the scansion a cutting off of the word is made. Where, however, after two feet nothing of the part of speech remains, it is a colon. The whole verse is a period.
Chapter XXI. On the marks of sentences Besides, there were certain marks of writings among the most celebrated authors, which the ancients set to poems and histories for the distinction of writings. A mark is a proper figure placed in the manner of a letter, to show the reasoning of each word, sentence and verse. There are twenty-six marks set to verses, with the names written below. The asterisk is placed at things that have been omitted, so that what seems to be wanting may shine forth through that mark. For a star is called astēr in Greek speech, from which asterisk is derived.
The obelus, that is, a stroke lying flat, is placed at words or sentences needlessly repeated, or in those places where some reading is marked with falsity, so that like an arrow it may cut the throat of superfluous things and pierce through the false. For an arrow in Greek is called obelos. The obelus with a point above is placed at the same places, about which it is doubted whether they ought to be removed or not. It is marked with falsity. The lemniscus, that is, a stroke lying between two points, is set at those places which the interpreters of Holy Scripture have translated in the same sense but in different words. The antigraphus with a point is placed where in translations a different sense is held. The asterisk with an obelus: Aristarchus used this properly at those verses which were not set in their own place. The paragraph is placed to separate things from things that run together in connection, as in the Catalogue places are separated from places and regions from regions, in the Contest prizes from prizes, and contests from different contests. The positura is a figure contrary to the paragraph and so formed because, as that marks the beginnings, this separates the ends from the beginnings. The cryphia, the lower part of a circle with a point, is placed at those places where a hard and obscure question could not be opened or solved. The antisigma is placed at those verses whose order is to be changed. It is found so placed in the ancient authors. The antisigma with a point is placed at those places where in the same sense there are double verses, and it is doubted which should rather be chosen. The diple: our writers set this in the books of ecclesiastical men to separate or to point out the testimonies of the Holy Scriptures. The diple periestigmenē: Leogoras of Syracuse first set this at Homeric verses to separate Olympus from heaven. The diple periestigmenē, that is, with double points: the ancients set this at those places which Zenodotus of Ephesus had wrongly added, or taken away, or changed. Our own writers have used it in these also. The diple with an obelus is inserted to separate the periods in comedies or tragedies. The reversed diple with an obelus, whenever strophe and antistrophe are brought in. The reversed mark with an obelus is placed at things which look back to something, as: “Is it we who strive to overturn your Phrygian fortunes from the foundation? we? or he who threw the wretched Trojans before the Achaeans?” The diple with an obelus above is placed at changes of conditions of places, times and persons. The upright and reversed diple with an obelus above is placed, the unit being ended in its own place, and signifies that what follows is also similar. The ceraunium is placed whenever many verses are disapproved and are not each marked by an obelus; for keraunion means thunderbolt. The chrēsimon: this alone is placed at the will of each person to note something. Phi and Rho, that is, phrontis: this is placed, where there is some obscurity, on account of concern. The upper anchor is placed where some matter is altogether great. The lower anchor, where something is declared very basely or less fittingly. The coronis mark is set only at the end of a book. The alogos is a mark applied to faults. Other little marks of books are also made, for recognizing what is set forth at the edges of the pages, so that when the reader finds such a sign in the margin, running back to the text he may know that it is the exposition of the same discourse or little verse, whose like he finds in the mark lying above.