The purpose of this paper is twofold. It attempts to introduce Arthur Collier to the contemporary reader of philosophy and to reveal some of the unique features of his thought. Part one is devoted to the first purpose and parts two and three to the second. Part three also contains a discussion on two impossibilities in Collier’s system: these are material substance and a centaur. Material substance turns out to be an ill-formed notion and the centaur, at the very least, (...) is not locatable in experience. (shrink)