The earliest surviving copy of St Jerome’s Vulgate version of the Gospels is a manuscript produced in Italy (perhaps in Verona) in about 410-420 AD, now in St Gallen, Stiftsbibliothek, Cod. Sang. 1395.
The following leaf contains the text of John 16:30 – 17:8.
Of this fragment, M.B. Parkes says:
“The oldest known method of presenting a text, found as early as the second century B.C. was to deploy features of layout to indicate the basic units of paragraph and capitulum, which represent the principal stages of an argument or narrative.
This method was employed here in an early codex copied in scriptio continua [unpunctuated writing with no word division] in Half-Uncial script.” 
The text is divided according to a system known as per cola et commata. A colon (pl. cola) was often used to indicate a major medial pause, or disjunction of sense, at the end of the colon. A comma (pl. commata) was a division of a colon, followed by a minor disjunction of the sense where it may be necessary to pause. Applied together, the cola et commata meant that the text was divided according to meaning in order to facilitate reading. Each meaningful element is laid out on a new line. The passage in the image above begins: “In hoc credidimus qui [pause] a deo existi [pause] Respondit eis iesus modo [pause]…..” (By this we believe that [pause] you have come from God [pause] Jesus answered them [pause]….”. The word ‘respondit’ (answered) does not follow ‘existi’ (you have come), but is entered on a new line to mark a new semantic element.
In his prologue to the book of Ezekiel, Jerome writes that ‘which is written per cola et commata conveys more obvious sense to the readers’, adding, elsewhere, that he encountered this system in copies of the speeches of Demosthenes and Cicero.
“[The text was] annotated by a scribe contemporary with the text, who has been plausibly identified with St Jerome himself. Each capitulum (as it is called by the annotator) begins on a new line with a littera notabilior set out to the left in the margin. Grammatical and sense elements within the boundaries of a capitulum are not identified, and such pauses as may be necessary were left to the discretion of a reader.
The numerals in the margins are to facilitate the use of the text with canon tables which indicate parallel passages in the other Gospels.” 
 M.B. Parkes, Pause and Effect. An introduction to the History of Punctuation in the West (Aldershot: Scolar Press, 1992), p. 161.