A man is not accountable for what occurs during sleep; as he has not then the use of his reason, wherein consists man's proper action.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic action reason
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

“Were anything presented to the imagination or sense of the first man, not in accordance with the nature of things, he would not have been deceived, for his reason would have enabled him to judge the truth. Reply Obj. 4: A man is not accountable for what occurs during sleep; as he has not then the use of his reason, wherein consists man's proper action. Reply Obj. 5: If anyone had said something untrue as regards future contingencies, or as regards secret thoughts, man in the primitive state would not have believed it was so: but he might have believed that such a thing was possible;” source