Latin punctuation is one of those classicist trade-secret things. To understand it fully takes intense study, and most classicists have views, no doubt dogmatically held. I am no purist. The bottom line for me is that Latin punctuation is just not as rule-bound as punctuation in English. Not that that is a bad thing. It’s just a different tradition. School texts have far more punctuation than scholarly critical editions. Some of the I Tatti editions seem almost allergic to punctuation. Editing a Neo-Latin text has made me newly aware of this issue, since I am frequently having to make decisions about where to put commas (trying to keep them to a minimum consistent with clarity), whether to use semi-colons (almost never), and so on. Early modern printed editions are notoriously punctuation happy. It sometimes seems as if the printer loaded a shotgun with commas, colons, and periods and fired at the page. Here is a taste:

Joannis Petri Maffeii Bergomatis E Societate Jesu Historiarum Indicarum Libri XVI (Vienna: Bernardi, 1752; orig. 1588), p. 6.

A more minimal, modern punctuation might be:

… illud praesertim summo conatu pervestigare num quis ab Atlantico in Eoum Oceanum vel mari vel terra transitus foret. Quippe iam tum, praeter acerrimum propagandae Christianae fidei studium, ad beatas etiam Arabiae gazas et Indici litoris opulenta commercia mentem et cogitationem adiecerat.

Although as a rule I would rather not have commas around prepositional phrases like praeter .. studium, it seems useful for comprehension in this case.

Various authors have explained their practices recently. My main guides are Cynthia Damon, who has an excellent discussion in the preface to her Oxford Classical Text of Caesar’s De bello civili, and Milena Minkova, whose wonderful Neo-Latin anthology I recommend heartily to anyone who wants to sample the best Latin writing in the early modern period. They both recommend a restrained approach, but Minkova insists that ablatives absolute, for example, should almost always be enclosed in commas. Damon (wisely, in my view) reserves semi-cola for independent clauses in indirect discourse. Given the flexibility available to editors, the golden rule is: a well-punctuated text shows that the editor understands the text.

In investigating this issue I have been intrigued to see the degree of variation among the modern edited texts (mostly Teubners and OCTs) reproduced in PHI, and I have never seen any collection of instances of variation or consensus among them. So, for those who might be interested in such things, here is my working list. The second column represents my policy, based on my own intuition and observations from PHI.