The first principle to be observed is that relatively _purity is comparative_. This is a commonplace of all personal estimates. However much we may adhere to the conception of a moral standard, which is abstract and unvarying, we realize that there are also personal standards which vary very much. We do not, for instance, consider a cat to be guilty of murder when she kills a bird; we do not execute her as we execute men who have taken human life. We do not even condemn lions or tigers as homicidal criminals, though we may kill them in self-defence, thus showing that it is not the distinction between taking animal and human life which constitutes the crime; it is the difference between the killers. Nor is it true that we draw a distinction merely between animal and human responsibility, for even in the human kingdom we apply a comparative moral standard; we do not consider a savage who steals or kills as being guilty to the extent which a civilized European would be who performed a similar act. We are in fact constantly applying a comparative standard to the comparative intelligences of individuals, and quite rightly, for all intelligence and moral sense is graded from brute-beast to savage-man and upwards. We must be careful not to avoid this standard of comparative values in approaching sex morality. So long as we admit that at least there are acts and principles which, taken in the abstract, approach purity more nearly than others, we must not judge all individuals by the same standard. We must not consider a very ordinary, unintelligent, animal-blooded young man as being excessively sinful for having a vivid sex experience; perhaps he is living right up to the level of his imperfect standard. We must not expect people to be more moral than they can be, though it is the duty of Church and religion to educate them to see that there are better standards. The second principle is simple, but of the deepest importance. It consists of the proposition that variety and not uniformity is the fundamental rule of nature, or, as Christians would hold, the intention of God.