Assiduity makes drunkenness a mortal sin, not on account of the mere repetition of the act, but because it is impossible for a man to become drunk assiduously, without exposing himself to drunkenness knowingly and willingly, since he has many times experienced the strength of wine and his own liability to drunkenness.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic repetition strength
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“"We learn that we should shun drunkenness, which prevents us from avoiding grievous sins. For the things we avoid when sober, we unknowingly commit through drunkenness." Therefore drunkenness, properly speaking, is a mortal sin. Reply Obj. 1: Assiduity makes drunkenness a mortal sin, not on account of the mere repetition of the act, but because it is impossible for a man to become drunk assiduously, without exposing himself to drunkenness knowingly and willingly, since he has many times experienced the strength of wine and his own liability to drunkenness. Reply Obj. 2: To take more meat or drink than is necessary belongs to the vice of gluttony, which is not always a mortal sin: but knowingly to take too much drink to the point of being drunk, is a mortal sin.” source