An angry man is said to be open, not because it is clear to him what he ought to do, but because he acts openly, without thought of hiding himself.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic hiding thoughts
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17897/pg17897-images.html

Context

“But the passion of anger forestalls the perfect judgment of reason, as though it listened but imperfectly to reason, on account of the commotion of the heat urging to instant action, which commotion is the material element of anger. In this respect it hinders the judgment of reason. Reply Obj. 2: An angry man is said to be open, not because it is clear to him what he ought to do, but because he acts openly, without thought of hiding himself. This is due partly to the reason being hindered, so as not to discern what should be hidden and what done openly, nor to devise the means of hiding; and partly to the dilatation of the heart which pertains to magnanimity which is an effect of anger:” source