Falsity is attributed to the imagination, as it represents the likeness of something even in its absence.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic likeness falsity
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

“Falsity is said not to be proper to sense, since sense is not deceived as to its proper object. Hence in another translation it is said more plainly, "Sense, about its proper object, is never false." Falsity is attributed to the imagination, as it represents the likeness of something even in its absence. Hence, when anyone perceives the likeness of a thing as if it were the thing itself, falsity results from such an apprehension; and for this reason the Philosopher says (Metaph. v, 34) that shadows, pictures, and dreams are said to be false inasmuch as they convey the likeness of things that are not present in substance.” source