The Institutes, Book 5
Keeping to the Hours for Food
So a monk who wants to go on to the struggle of the inner conflicts should lay this down as a safeguard for himself from the start. He will not in any case let himself be overcome by any delicacies. He will not take anything to eat or drink before the fast is over and the proper hour for a meal has come, outside mealtimes. Nor, when the meal is over, will he let himself take a morsel, however small. And likewise he will keep the set time and amount of sleep laid down by the rule. For that self-indulgence must be cut off in the same way as the sin of unchastity has to be rooted out. If a man cannot check the unnecessary desires of his appetite, how will he be able to put out the fire of fleshly lust? And if a man cannot control passions that are openly visible and only small, how will he be able, with sober discernment, to fight against those that are secret and stir him when no one is there to see? That is why strength of mind is tested in each separate impulse and in every kind of passion. And if it is overcome by very small and visible desires, each man’s own conscience must bear witness for himself how it will hold out against those that are truly great and powerful and hidden.