Therefore in man the essence of the intellectual soul, the sensitive soul, and the nutritive soul, cannot be the same.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic soul essence
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
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Context

“For corruptible and incorruptible are not of the same substance. But the intellectual soul is incorruptible; whereas the other souls, as the sensitive and the nutritive, are corruptible, as was shown above (Q. 75, A. 6) . Therefore in man the essence of the intellectual soul, the sensitive soul, and the nutritive soul, cannot be the same. Obj. 2: Further, if it be said that the sensitive soul in man is incorruptible; on the contrary, "corruptible and incorruptible differ generically," says the Philosopher, Metaph. x (Did. ix, 10) . But the sensitive soul in the horse, the lion, and other brute animals, is corruptible.” source