As potentiality is directed towards act, potential beings are differentiated by their different acts, as sight is by color, hearing by sound.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic potential sight
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17611/pg17611-images.html

Context

“Logically considered, however, there is but one genus of all bodies, since they are all included in the one notion of corporeity. Reply Obj. 3: The form of corporeity is not one and the same in all bodies, being no other than the various forms by which bodies are distinguished, as stated above. Reply Obj. 4: As potentiality is directed towards act, potential beings are differentiated by their different acts, as sight is by color, hearing by sound. Therefore for this reason the matter of the celestial bodies is different from that of the elemental, because the matter of the celestial is not in potentiality to an elemental form. _______________________” source