and matter: what takes place in the body furnishes God the occasion to permit a change to take place in the soul, and vice versa. It soon became evident however that, if there is an absolute substance, it is impossible for a finite being to be a cause at all. How can anything produce an effect beyond its own being in some other thing? Not only the interaction between spirit and matter but all interaction between finite beings is impossible, and divine causality alone remains possible. In this way first the psycho-physical problem and then the problem of causality conceived as a whole came to be regarded as insoluble and philosophy resolved itself into theology.
After a number of Cartesians had prepared the way for this conception, it was clearly and definitely elaborated by Arnold Geulincx (1623-1669) and Nicholas Malebranche (1648-1715).
Geulincx, originally a Catholic (he was born at Louvain), but later a convert to Protestantism, experienced a vigorous opposition both from Protestant as well as from Catholic scholasticism on account of his Cartesianism. During his latter years he occupied the chair of philosophy at the university of Leyden. His most characteristic work is his ethics (1665, complete 1675). In order to do right, man must learn to understand his position in the world; self-examination (inspectio sui) is therefore the foundation of ethics. It reveals the fact that intellect and will are all that really belongs to my Self. My body on the other hand is a part of the material universe where I can accomplish nothing. For I am only responsible for the things of which I can know the origin, and this knowledge is limited to my intellect and will. My activity cannot transcend my essential nature (i.e. my intellect and will). It is utterly impossible for a thing to produce changes be-
