I see that I had forgotten in my earlier comment this explicit use of the term "Quantity" by Martin Ferguson Smith in his translation of the Inscription of Diogenes of Oinoanda. That needs to be referenced in this discussion:
Fr. 34 lower margin (Epic. Sent. 3)
[The quantitative limit of pleasure is the] removal of all pain. [Whoever experiences pleasure, so long as it continues, cannot ever be troubled] by pain of body or of mind or [of both together].