Full Idea
Our mind both abstracts the species from images when it attends to the general nature of things, and understand the species in the images when it has recourse to the images in order to understand the things whose species it has abstracted.
Gist of Idea
The mind abstracts generalities from images, but also uses images for understanding
Source
Thomas Aquinas (Summa Theologicae [1265], Ch.5 Q85.1)
Book Reference
Aquinas,Thomas: 'Summa Theologicae (Concise)', ed/tr. McDermott,Timothy [Christian Classics 1991], p.134
A Reaction
Geach claims that the second half of this idea means that Aquinas is not an abstractionist, but he seems to be explictly abstractionist about the way in which we create higher level concepts from lower ones.