1265–1273 · Thomas Aquinas, Summa Theologica II-II, q. 147, a. 4, ad 3
Reply to Objection 3: Apparently a distinction should be made with regard to pilgrims and working people. For if the pilgrimage or laborious work can be conveniently deferred or lessened without detriment to the bodily health and such external conditions as are necessary for the upkeep of bodily or spiritual life, there is no reason for omitting the fasts of the Church. But if one be under the necessity of starting on the pilgrimage at once, and of making long stages, or of doing much work, either for one's bodily livelihood, or for some need of the spiritual life, and it be impossible at the same time to keep the fasts of the Church, one is not bound to fast: because in ordering fasts the Church would not seem to have intended to prevent other pious and more necessary undertakings. Nevertheless, in such cases one ought seemingly, to seek the superior's dispensation; except perhaps when the above course is recognized by custom, since when superiors are silent they would seem to consent. Reply to Objection 4: Those poor who can provide themselves with sufficient for one meal are not excused, on account of poverty, from keeping the fasts of the Church. On the other hand, those would seem to be exempt who beg their food piecemeal, since they are unable at any one time to have a sufficiency of food.