The relation of efficient causality, of efficient cause and effect, between two objects of thought, is sometimes set down as a sure sign of a (major) real distinction between them.(157) And the reason alleged is that a thing cannot be the efficient cause of itself: the efficient cause is necessarily extrinsic to the effect and cannot be really identical with the latter. It is to be noted that this test applies to reality as actually existing, as producing or undergoing change, and that it is derived from our sense experience of reality in process of change. But since our concept of efficient causality has its origin in our internal experience of our own _selves_ as active agents, as causing some portion of what enters into our experience, the test seems to assume that we have already introduced into this experience a real distinction between the self and what is caused by the self. It is not clear that the relation of efficient cause to effect, as applied to created causes, can precede and reveal, in our experience, the relation of what is _really one_ to what is _really other_, in this experience. If the reality revealed to us in our direct experience, the phenomenal universe, has been brought into existence by the creative act of a Supreme Being, this, of course, implies a real distinction between Creator and creature. But it does not seem possible in this case, or indeed in any case, to prove the existence of the causal relation antecedently to that of the real distinction, or to utilize the former as an index to the latter. Two distinct thought-objects are regarded as _really_ distinct (1) when they are found to exist separately and apart from each other in time or space, as is the case with any two individuals such as John and James, or a man and a horse; (2) when, although they are found in the same individual, one of them at least is separable from the other, in the sense that it can actually exist without that other: for example, the soul of any individual man can exist apart from the material principle with which it is actually united to form this living human individual; the individual himself can exist without the particular accidental modes, such as sitting, thinking, speaking, which actually affect his being at any particular instant of his existence. From this we can gather in the first place that the distinction between two “individuals,”—individual “persons” or individual “things”—is a real distinction in the fullest and plainest sense of this expression, a major or absolute real distinction. It is, moreover, not merely real but actual. Two existing “individuals” are always actually divided and separate from each other, while each is actually one or actually undivided in itself. And they are so “independently of the consideration of the mind”.