Philosophical literature has exhibited considerable interest in the ancient doctrine of materialism. Mechanism and determinism, which in the first place need to be distinguished, are frequently and perhaps rightly associated with materialism. A general observation might first be made. While it is all too often overlooked, the philosophical theory called materialism in no way changes men. Men protest when they feel pain, they choose when they can. No philosophical or scientific theory by itself could alter this. It is of course true that a theory may alter the ways in which explain and understand those facts and it is also true that this understanding might provide a basis for new policies and decisions. When Darwin's evolutionary hypothesis showed that man was a "risen animal," some philosophers, many theologians, and still more people simply argued that the soul was interjected at the time of human conception, thus marking human beings as distinct from lower animals.