inconsistent with their conception. They may be thinking substances, and it cannot be denied that in this system a monad may become, if God wishes it, a thinking soul. If on the one hand it is not impossible, there is no way, on the other hand, of proving that it may be so. Why may there not be several orders of monads which are unable to pass from one class to another? Why may there not be monads having merely mechanical properties; others of a higher order, containing the principle of life, like plant souls; still higher sensitive souls; and finally free and intelligent souls endowed with personality and immortality? Leibniz's system is no more opposed than any other to these orders.
If, however, by a bolder hypothesis, the possibility of a monad's passing from one order to another be admitted, there would still be nothing here degrading to the true dignity of man, for, after all it must be recognized that the human soul in its first state is hardly anything more than a plant-soul which lifts itself by degrees to the condition of a thinking soul. Therefore there will be no contradiction in admitting that every monad contains potentially a thinking soul. Should such a hypothesis be repugnant, I still maintain that the monadological system does not force one to it, since monadism quite as well as the popular atomism can admit a scale of substances essentially distinct from one another.
Another objection which the Leibnizian excites, and one which Arnauld does not fail to raise in one of his letters, is that the system of monads weakens the argument of a first mover, since it implies that matter can be endowed with active force and consequently with spontaneous motion. Leibniz does not meet this objection in a convincing manner and says merely that recourse must be had to God to explain the co-ordination of movements. This, however, avoids the point, for the co-ordination has no relation to the argument of the first mover, only to that of the ordering and of the arrangement which is a wholly different matter. We may, however, remark that Leibniz, in order to establish the reality of the force in corporeal substance, much more frequently uses the fact of resistance to motion, than that of the so-called spontaneous motion. For instance, one of his principal arguments is that a moving body, when it comes in contact with another, loses motion in proportion to the resistance which the other
