This is the truth which underlies what is called the doctrine of Transubstantiation, so extraordinarily misunderstood by the ordinary Protestant. But such is the fate of occult truths when they are presented to the ignorant. The "substance" that is changed is the idea which makes a thing to be what it is; "bread" is not mere flour and water; the idea which governs the mixing, the manipulation, of the flour and water, that is the "substance" which makes it "bread," and the flour and the water are what are technically called the "accidents," the arrangements of matter that give form to the idea. With a different idea, or substance, flour and water would take a different form, as indeed they do when assimilated by the body. So also chemists have discovered that the same kind and the same number of chemical atoms may be arranged in different ways and thus become entirely different things in their properties, though the materials are unchanged; such "isomeric compounds" are among the most interesting of modern chemical discoveries; the arrangement of similar atoms under different ideas gives different bodies.
What, then, is this change of substance in the materials used in the Eucharist? The idea that makes the object has been changed; in their normal condition bread and wine are food-stuffs, expressive of the divine ideas of nutritive objects, objects fitted for the building up of bodies. The new idea is that of the Christ nature and life, fitted for the building up of the spiritual nature and life of man. That is the change of substance; the object remains unchanged in its "accidents," its physical material, but the subtle matter connected with it has changed under the pressure of the changed idea, and new properties are imparted by this change. They affect the subtle bodies of the participants, and attune them to the nature and life of the Christ. On the "worthiness" of the participant depends the extent to which he can be thus attuned.
The unworthy participant, subjected to the same process, is injuriously affected by it, for his nature, resisting the pressure, is bruised and rent by the forces to which it is unable to respond, as an object may be broken into pieces by vibrations which it is unable to reproduce.