From the Introduction to the Devout
Life III, ch. 23
... I disapprove of long and immoderate fasting, especially for the young. I have learned by experience that when the colt grows weary it turns aside, and so when young people become delicate by excessive fasting, they readily take to self-indulgence.... A want of moderation in the use of fasting, discipline and austerity has made many a one useless in works of charity during the best years of his life...
Fasting and labor both exhaust and subdue the body. If your work is necessary or profitable to God’s Glory, I would rather see you bear the exhaustion of work than of fasting. Such is the mind of the Church, who dispenses those who are called to work for God or their neighbor even from her prescribed fasts. One man finds it hard to fast, another finds it as hard to attend the sick, to visit prisons, to hear confessions, preach, minister to the afflicted, pray, and the like. And the last hardship is better than the other; for while it subdues the flesh equally, it brings forth better fruit. And as a general rule it is better to preserve more bodily strength than is absolutely necessary, than to damage it more than is necessary. Bodily strength can always be lowered if needful, but we cannot restore it at will. It seems to me that we ought to have in great reverence that which our Saviour and Redeemer Jesus Christ said to His disciples, “Eat such things as are set before you.” To my mind there is more virtue in eating whatever is offered you just as it comes, whether you like it or not, than in always choosing what is worst; for although the latter course may seem more ascetic, the former involves greater submission of will, because by it you give up not merely your taste, but your choice; and it is no slight austerity to hold up one’s likings in one’s hand, and subject them to all manner of accidents.