What a man sets apart for the highest thing he must not turn around and swallow himself. The tithe, the firstborn of the flock, the portion promised in a vow, all of it is fenced off from ordinary appetite, and the fence is the whole point. The moment the consecrated grain becomes just dinner, the offering has collapsed back into consumption. The sacred cannot be eaten.
Discipline of this shape is the refusal to consume what you have dedicated to something above you. The best of the harvest is withheld from the mouth precisely because it belongs to a purpose higher than the mouth. A person who devours everything he produces has kept nothing back for what matters most. Set the finest portion aside, and let it stay set aside.