The Greek writing visible in the image reads:
ΦΙΛΟΔΗΜΟΥ ΠΕΡΙ ΦΥΣΕΩΣ
This translates into English as:
Of Philodemus, On Nature
ΠΕΡΙ ΚΑΚΙΩΝ Ά
About vices - part A
Interestingly, as written, it is ΚΑΚΙωΝ not ΚΑΚΙΩΝ.
Originally there was no minuscule/majuscule (uppercase/lowercase) distinction in Greek writing (or Latin for that matter). They did have handwritten forms designed to be written faster, which is what the ω is in this case. Of course, those handwritten forms evolved often evolved into the forms we think of as lowercase forms today.
They identified it by title as a copy of a known work. This information appears very early in the article.