Scholasticism has taken the notion of substance from common sense and made it very technical and articulate. Few things would seem to have fewer pragmatic consequences for us than substances, cut off as we are from every contact with them. Yet in one case scholasticism has proved the importance of the substance-idea by treating it pragmatically. I refer to certain disputes about the mystery of the Eucharist. Substance here would appear to have momentous pragmatic value. Since the accidents of the wafer don’t change in the Lord’s supper, and yet it has become the very body of Christ, it must be that the change is in the substance solely. The bread-substance must have been withdrawn, and the divine substance substituted miraculously without altering the immediate sensible properties. But tho these don’t alter, a tremendous difference has been made, no less a one than this, that we who take the sacrament, now feed upon the very substance of divinity. The substance-notion breaks into life, then, with tremendous effect, if once you allow that substances can separate from their accidents, and exchange these latter.

This is the only pragmatic application of the substanceidea with which I am acquainted; and it is obvious that it will only be treated seriously by those who already believe in the ‘real presence’ on independent grounds.

—William James, Pragmatism