"The notions about heaven and hell, with which the people of "Christian" nations are more or less familiar, are probably the crude remains of earlier and more philosophical ideas. If we consider hell and heaven to be states of mind instead of places, it is easy to see the reason for such ideas. For each man, in the course of his normal living, enters periodically into states of great happiness and great unhappiness, and further more, while he is in them, he is apt to forget everything else. The mind, in other words, builds its own world. Is it so strange, then, to imagine that after the death of the body this same process may continue, in an even more intense degree, since no physical interruptions are possible?"