Given the evidence available today, we know that the later Middle Ages knew strong forms of idealism. However, Plato alone will not do to explain some of its features. Aristotle was the most important philosophical authority in the thirteenth and fourteenth centuries, but until now no one dared explore in his thought the roots of this idealism because of the dogma of realism surrounding him. I challenge this dogma, showing that the Stagirite contained in his thought the roots of idealist (...) aspects that will be developed, namely by Dietrich of Freiberg and Eckhart of Hochheim, into a fully idealist epistemology. (shrink)