On the other hand, just in the degree in which distinctness is introduced into the sensations, so that they are not simply experienced as they come, but are related to one another so that their reason for existence, their spiritual meaning, is ascertained, just in that degree is the soul master of itself. In Leibniz's own words: "Distinct knowledge or intelligence has its place in the true use of reason, while the senses furnish confused ideas. Hence we can say that we are free from slavery just in the degree that we act with distinct knowledge, but are subject to our passions in just the degree that our ideas are confused;" that is, not really representative of things as they are. "Intelligence is the soul of liberty." This psychological explanation rests, of course, upon the foundation principle of the Leibnizian philosophy. Spirit is the sole reality, and spirit is activity. But there are various degrees of activity, and each grade lower than the _purus actus_ may be rightfully regarded as in so far passive. This relative passivity or unreality constitutes the material and hence the sensuous world. One who has not insight into truth, lives and acts in this world of comparative unreality; he is in bondage to it. From this condition of slavery only reason, the understanding of things as they are, can lift one. The rational man is free because he acts, in the noble words of Spinoza, _sub specie æternitatis_. He acts in view of the eternal truth of things,--as God himself would act.