The final result of our discussion, then, is that the causal postulate according to which events are completely determined by antecedent events leads to the belief that the stream of events is discontinuous. This belief is inherently self-contradictory, and therefore ultimately untrue. The principle of Ground and Consequence cannot therefore be adequately represented by the causal postulate, however indispensable that postulate may be in practice. Whether the conception of a continuous stream of events affords any better formulation of the principle of the systematic interconnection of all Reality, we shall be better able to judge after the discussions of our third book. If it does not, we shall have to recognise that the conception of temporal succession itself is not adequate to express the way in which the Many and the One of real existence are united, _i.e._ that time is not real, but only phenomenal. § 10. A word may be said here as to the nature of the “necessity” which we ascribe to the connection of cause and effect. There can be little doubt that the origin of this “necessity” must be found in our own feelings of constraint when our action is dictated from without. It is clear, however, that we have no right to ascribe this feeling of constraint to the event which is determined by its connection with the rest of the system of Reality. All that is meant in science by the “necessity” of the causal relation is that given the conditions the result follows, and not otherwise. In other words, _if_ you assert the existence of the conditions, you are logically bound to assert the existence of the result. The constraint thus falls within ourselves, and is of a hypothetical kind. So long as your purpose is to think logically, you feel constraint or compulsion when, after asserting the condition, you seek for any reason to escape asserting the result. It is one of the conspicuous services of Hume to philosophy, that he for the first time brought out clearly this subjective character of the “necessity” of the causal relation, though it must be admitted that he went on to complicate his argument by an admixture of error when he sought to base the necessity of the logical inference from Ground to Consequence on the psychological principle of Association.