This illustrates a basic principle of nature: deprivation is not just a lack of something, rather, it is, at the same time, also possession of something else - a strength and an incentive to overcome the sense of lack. Impelled by the law of nature itself, a person who considers himself to be deprived of or lacking something develops a strength or urge to make efforts to acquire that which he thinks he is deprived of or lacks. This inner urge keeps him active until he reaches his goal.
