Tristitia quamlibet operationem impedit, nunquam enim illud quod cum tristitia facimus, ita bene facimus sicut illud quod facimus cum delectatione, vel sine tristitia, quia voluntas est causa operationis humanae, unde quando operatio est de qua aliquis contristatur, necesse est quod actio debilitetur.
Sadness hinders any action, for we never do that which we do with sadness as well as that which we do with pleasure, or without sadness, because the will is the cause of human action, and consequently when we do something that gives pain, the action must of necessity be weakened in consequence.
Philosophus dicit, in X Ethic., quod delectatio perficit operationem, sed e contrario tristitia impedit.
The Philosopher says (Ethic. x, 4) that "pleasure perfects action," whereas on the other hand, "sadness hinders it" (Ethic. x, 5).