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.
God alone, it further follows, is wholly free. In him alone are understanding and will wholly one. In him the true and the good are one; while every created intelligence is subject in some degree to sensuous affection, to passion. "In us, besides the judgment of the understanding, there is always mixed some unreal idea of the sensation which gives birth to passions and impulses, and these traverse the judgment of the practical understanding." Freedom, in fine, is not a ready made garment with which all men are clothed to do with as they will. It is the ethical ideal; it is something to be attained; it is action in conformity with reason, or insight into the spiritual nature of reality and into its laws; it is not the starting-point, it is the goal. Only with a great price do men purchase such freedom. It will be noticed at once that Leibniz comes very close to Plato in his fundamental ethical ideas. The unity of virtue and reason, of virtue and freedom,--these are thoroughly Platonic conceptions. To both Plato and Leibniz reason is the ethical ideal because it is the expression of, nay, rather, _is_ the reality of the universe; while all else is, as Leibniz says, imperfect or unreal, since it is not an activity, or, as Plato says, a mixture of Being and Non-Being. Again, to both man bears a similar relation to this spiritual reality. In Plato's words, he participates in the Ideas; in those of Leibniz he reflects, as a mirror, the universe. To both, in a word, the reality, the true-self of the individual, is the spiritual universe of which it is an organic member. To both, therefore, man obtains freedom or self-realization only as he realizes his larger and more comprehensive identity with the Reason of the universe. With both, knowledge is the good, ignorance is the evil. No man is voluntarily bad, but only through lack of knowledge of the true Good. Leibniz, however, with a more developed psychology, supplements Plato in the point where the latter had the most difficulty,--the possibility of the feelings or of a love of pleasure overcoming knowledge of the good. This possibility Plato was compelled to deny, while Leibniz, by his subtle identifying of the passions with lack of knowledge, or with confused knowledge, can admit it. "It is an imperfection of our freedom," says Leibniz, "which causes us to choose evil rather than good,--a greater evil rather than the less, the less good rather than the greater. This comes from the _appearances_ of good and evil which deceive us; but God, who is perfect knowledge, is always led to the true and to the best good, that is, to the true and absolute good."