Full Idea
The agent intellect abstracts intelligible species from phantasms insofar as through the power of the agent intellect we can take into our consideration the natures of the species without the individual conditions.
Gist of Idea
Species are abstracted from appearances by ignoring individual conditions
Source
Thomas Aquinas (Summa Theologicae [1265], Q85 Ad4)
Book Reference
Aquinas,Thomas: 'Treatise on Human Nature (Summa 1a 75-89)', ed/tr. Pasnau,Robert [Hackett 2002], p.161
A Reaction
There might be a threatened circularity here, in trying to decide which features to ignore and which to retain. If we saw a hundred horses with a white nose blaze, we still wouldn't be sure that this was essential to a horse. Innate notions of species??