“We are drawn towards a thing, either because there is some good we are seeking from it, or because we cannot do without it. Sometimes the two motives coincide. Often however they do not. Each is distinct and quite independent. We eat distasteful food, if we have nothing else, because we cannot do otherwise. A moderately greedy man looks out for delicacies, but he can easily do without them. If we have no air we are suffocated, we struggle to get it, not because we expect to get some advantage from it but because we need it. We go in search of sea air without being driven by any necessity, because we like it. In time it often comes about automatically that the second motive takes the place of the first. This is one of the great misfortunes of our race. A man spokes opium in order to attain to a special condition, which he thinks superior; often, as time goes on, the opium reduces him to a miserable condition which he feels to be degrading; but he is no longer able to do without it.”