I wish the student to get this idea very clearly because this is really the crux of the passage from the Fourth Kingdom into the Fifth. The great problem of the future of evolution is the introduction of the Personal Factor. The reason why this is so is very simple when we see it. To take a thought from my own "Doré Lectures" we may put it in this way. In former days no one thought of building ships of iron because iron does not float; yet now ships are seldom built of anything else, though the relative specific gravities of iron and water remain unchanged. What has changed is the Personal Factor. It has expanded to a more intelligent perception of the law of flotation, and we now see that wood floats and iron sinks, both of them by the same principle working under opposite conditions, the law, namely, that anything will float which bulk for bulk is lighter than the volume of water displaced by it, so that by including in our calculations the displacement of the vessel as well as the specific gravity of the material, we now make iron float by the very same law by which it sinks. This example shows that the function of the Personal Factor is to analyze the manifestations of Law which are spontaneously afforded by Nature and to discover the Universal Affirmative Principle which lies hidden within them, and then by the exercise of our powers of Initiative and Selection to provide such specialized conditions as will enable the Universal Principle to work in perfectly new ways transcending anything in our past experience. This is how all progress has been achieved up to the present; and is the way in which all progress must be achieved in the future, only for the purpose of evolution, or growth from within, we must transfer the method to the spiritual plane.