“ Putting Locke’s doctrine into modern language, we may say that a man has the conception of cause primarily because he himself is a cause. The conception thus obtained we “project,” that is, transfer to external objects, so far as we may find it useful to do so. Thus it is by a sort of analogy that we say that the sun is the “cause” of daylight. The rival theory to Locke’s is that of Hume (Treatise, bk. i.) , who derives the conception from the unaided operation of custom. When one object, A, has been noticed frequently to precede another object, B, an association between A and B is generated ”

“ Causa sui is a term applied to God by Spinoza to denote that he is dependent on nothing and has no need of any external thing for his existence. Vera causa is a term used by Newton in his Principia, where he says, “No more causes of natural things are to be admitted than such as are both true and sufficient to explain the phenomena of those things”; verae causae must be such as we have good inductive grounds to believe do exist in nature, and do perform a part in phenomena analogous to those we would render an account of. ”

“ Thus when one thing B is regarded as taking place in consequence of the action of another thing A, then A is said to be the cause of B, and B the effect of A. The philosophical problems connected with causation are both metaphysical and psychological. The metaphysical problem is part of the whole theory of existence. If everything is to be regarded as causally related with simultaneous and prior things or actions, it follows logically that the investigation of existence must, by hypothesis, be a regress to infinity, i.e. that we cannot conceive a beginning to existence. ”