501. As regards the churches that in course of time succeeded one another, and of which it is said that one was born from another, the case with them was the same as it is with fruits, or with their seeds. In the midst of these, that is, in their inmosts, there are as it were fruits of the fruits, or seeds of the seeds, from which live as it were in regular order the successive parts. For the more remote these are from the inmost toward the circumference, the less of the essence of the fruit or of the seed is there in them, until finally they are but the cuticles or coverings in which the fruits or seeds terminate. Or as in the case of the brain, in the inmost parts of which are subtle organic forms called the cortical substances, from which and by which the operations of the soul proceed; and from which in regular order the purer coverings follow in succession, then the denser ones, and finally the general coverings called meninges, which are terminated in coverings still more general, and at last in the most general of all, which is the skull.