I was able finally to look at Bonitz yesterday. Recall that I was puzzled about Caston's citation of Bonitz on Aristotle's use of opsis to mean the act or actuality of visual perception. I wrote:
[Caston] cites Bonitz as an authority but oddly gives impossible Bekker numbers for the relevant text: his note 26 on p. 762 reads "Against Horn 1994, p. 29. See Bonitz (1870) 1955, 553a55-554b7, esp. 553a55-b30." (Bekker page 553 has only 32 lines.)I confess I was misled because at the Brown BACAP seminar last week, someone had said that, for opsis meaning an 'act of seeing', Caston "cites a text in the 500s"--at which point we all turned to Historia Animalium 553a, a discussion of bees, not finding anything there in support Caston's claim.
As it turns out, Caston's citation is in order. The page number, 553, refers to the Index Aristotelicum, not to Aristotle's works, and on that page the entry for opsis begins on line 55 in the first column.
(To be perfectly precise, however, Bonitz' listing of instances of opsis as meaning ipsa actio videndi is found at b16-30, whereas a 55-b16 concerns the acceptation, facultas videndi.)