DURATION AND TIME are commonly used as synon ymous terms. In recent philosophy, however, great stress has been laid on the need of differentiating between them in order to avoid certain confusions. The difference has been expressed most clearly by Bergson, who, however, has only revived and elaborated the distinction drawn already by Spinoza (see Letter XII. in A. Wolf, The Correspondence of Spinoza, p. 119). Time is commonly conceived abstractly and is thought of as composed of discrete instants or moments which follow one another in a uniform manner. For the purposes of science such an abstraction is often necessary. But real time, time as it actually passes, as it is actually experienced and lived in the world of changing events is not composed of such instants which replace one another. It is dura tion, that is a continuous change in which "the past gnaws into the future and swells as it advances" (H. Bergson, Creative Evolution, p. 5.) When time is conceived as a succession of discrete parts it is incomprehensible how any period of time, say an hour, can ever elapse, seeing that it involves the sequence of an infinity of parts. Hence Zeno's paradox of Achilles and the tortoise. But real time is only apprehended in intuition, and is continuous duration. The abstract concept of Time, as com monly used in science, is the result of an attempt to assimilate it to Space, or at least to measure it by means of certain correlated positions in Space. Such is the view of Bergson, whose views may be summarized as follows. When science speaks of time it really refers to the motion of a body M on its trajectory. This motion is taken to represent time, and, by definition, is assumed to be uniform. Let M2, M3 ... be points which divide the path of the moving body, M, into equal parts from its starting point Mo onwards. Then it will be said that 1, 2, 3, ... units of time have elapsed when M is at M2, M3.... Hence to con sider the state of the universe at a certain time, say t, is simply to consider its state when M will be at the position Mt. No attention is paid to the actual flow of time, much less to its effect, on consciousness. For only points or positions are taken into account. And all that is considered in connection with all other parts of the universe is their positions on their several paths. With each virtual position of M M2, M3, ... ) there is cor related a virtual position of all other moving bodies. But these correspondences in position are simultaneities which take no ac count of the flow of time, the continuous transitions from position to position in unbroken sequence. If real time could be measured by feeling, independently of physical events, then the sequence of physical events would continue to be expressed by the same equations, however much their actual tempo might be varied as judged independently by our duration-feeling. Science, as a mat ter of fact, has no symbols to express real succession or duration. See H. Bergson, Time and Freewill (i 910) ; see also the article SPACE-TIME. (A. Wo.)