Important source

The PLatonic Tradition in the Middle Ages - chapter on Aquinas and Platonism:

http://books.google.ca/books?hl=en&lr=&id=40inxdElwAMC&oi=fnd&pg=PA279&dq=aquinas+form&ots=5nxbE4dfi6&sig=tOHcnE02gj-G1ZV9Rtehloh3r3E#PPA280,M1

also good for its sources.

ARgh. 282-284 not part of preview.