This defect of the Cartesian system operated as an impelling motive to those which succeeded.
1. Mind and matter, consciousness and existence, Descartes had fixed in the farthest separation from each other. Both, with him, are substances, independent powers, reciprocally excluding oppositions. Mind (_i. e._ in his view the simple self, the Ego) he regarded as essentially the abstraction from the sensuous, the distinguishing itself from matter and the separating of matter from itself; matter was essentially the complete opposition to thought. If the relation of these two powers be as has been given, then the question arises, how can there ever be a filiation (_Rapport_) between them? How, on the one hand, can the affections of the body work upon the soul, and on the other hand, how can the volition of the soul direct the body, if the two are absolutely distinct and opposed to each other? At this point, _Arnold Geulincx_ (a disciple of Descartes, born at Antwerp 1625, and died as professor of philosophy at Leyden 1669) took up the Cartesian system, and endeavored to give it a greater logical perfection. According to Geulincx neither the soul works immediately upon the body, nor the body immediately upon the soul. Certainly not the former: for though _I_ can determine and move my body in many respects arbitrarily, yet _I_ am not the cause of this movement; for I know not how it happens, I know not in what manner motion is communicated from my brain to the different parts of my body, and it is impossible that I should do that in respect of which I cannot see how it is done. But if I cannot produce motion in my body, much less can I do this outside of my body. I am therefore simply a contemplator of the world; the only act which is peculiarly mine is contemplation. But even this contemplation arises in a singular manner. For if we ask how we obtain our observations of the external world, we find it impossible that the external world should directly give them to us. For however much we may say that, _e. g._ in the act of seeing, the external objects produce an image in my eye or an impression in my brain as in wax, yet this impression or picture is after all only something corporeal or material, and cannot therefore come into my mind, which is absolutely distinct from every thing material. There remains, therefore, only that we seek the mediation of the two sides in God. It is God alone who can unite the outer with the inner, and the inner with the outer; who can make the outer phenomena to become inner representations or notions of the mind; who can thus bring the world within the mind’s observation, and the inner determinations of the will outward into deed. Hence every working, every act which unites the outer and inner, which brings the mind and the world into connection, is neither a working of the mind nor of the world, but only an immediate working of God. The movement of my limbs does not follow from my will, but only because it is the will of God that these movements should follow when I will. My will is an _occasion_ by which God moves my body—an affection of my body is an _occasion_ by which God brings within me a representation of the external world: the one is only the occasional cause of the other (hence the name occasionalism). My will, however, does not move God to move my limbs, but he who has imparted motion to matter and given it its laws, created also my will, and has so connected together the most diverse things, the movement of matter and the arbitrium of my will, that when my will puts forth a volition, such a motion follows as it wills, and the motion follows the volition without any interaction or physical influence exerted by the one upon the other. But just as it is with two clocks which go exactly alike, the one striking precisely as the other, their harmony is not the result of any reciprocal interacting, but follows because both have been fashioned and directed alike,—so is it with the movements of the body and the will, they harmonize only through that exalted artist who has in this ineffable way connected them together. We see from this that Geulincx has carried to its limit the dualistic basis of Descartes. While Descartes called the union of mind and matter a conjunction through power, Geulincx named it a miracle. There is consequently in this view no immanent, but only a transcendent mediation possible.