a planet in space, the knowledge of this act will hardly enable us to estimate the influence of the feeling on the whole of a life-story, and it is this very influence which we want to know. All foreseeing is in reality seeing, and this seeing takes place when we can reduce as much as we please an interval of future time while preserving the relation of its parts to one another, as happens in the case of astronomical predictions. But what does reducing an interval of time mean, except emptying or impoverishing the conscious states which fill it? And does not the very possibility of seeing an astronomical period in miniature thus imply the impossibility of modifying a psychological series in the same way, since it is only by taking this psychological series as an invariable basis that we shall be able to make an astronomical period vary arbitrarily as regards the unit of duration? [Sidenote: Difference between past and future duration in this respect.] Thus, when we ask whether a future action could have been foreseen, we unwittingly identify that time with which we have to do in the exact sciences, and which is reducible to a number, with real duration, whose so-called quantity is really a quality, and which we cannot curtail by an instant without altering the nature of the facts which fill it. No doubt the identification is made easier by the fact that in a large number of cases we are justified in dealing with real duration as with astronomical time. Thus, when we call to mind the past, i.e. a series of deeds done, we always shorten it, without however distorting the nature of the event which interests us. The reason is that we know it already; for the psychic state, when it reaches the end of the _progress_ which constitutes its very existence, becomes a _thing_ which one can picture to oneself all at once. Here we find ourselves in the same position as the astronomer, when he takes in at a glance the orbit which a planet will need several years to traverse. In fact, astronomical prediction should be compared with the recollection of the past state of consciousness, not with the anticipation of the future one. But when we have to determine a future state of consciousness, however superficial it may be, we can no longer view the antecedents in a static condition as things; we must view them in a dynamic condition as processes, since we are concerned with their influence alone. Now their duration is this very influence. Therefore it will no longer do to shorten future duration in order to picture its parts beforehand; one is bound to _live_ this duration whilst it is unfolding. As far as deep-seated psychic states are concerned, there is no perceptible difference between foreseeing, seeing, and acting. [Sidenote: The determinist argument that psychic phenomena are subject to the law "same antecedents, same consequent."]