67. Many of us, beloved brethren, declare the substance of the Father and the Son to be one in such a spirit that I consider the statement to be quite as much wrong as right. The expression contains both a conscientious conviction and the opportunity for delusion. If we assert the one substance, understanding it to mean the likeness of natural qualities and such a likeness as includes not only the species but the genus, we assert it in a truly religious spirit, provided we believe that the one substance signifies such a similitude of qualities that the unity is not the unity of a monad but of equals. By equality I mean exact similarity so that the likeness may be called an equality, provided that the equality imply unity because it implies an equal pair, and that the unity which implies an equal pair be not wrested to mean a single Person. Therefore the one substance will be asserted piously if it does not abolish the subsistent personality or divide the one substance into two, for their substance by the true character of the Son’s birth and by their natural likeness is so free from difference that it is called one.