It is acting that provides man with the notion of time and makes him aware of the flux of time. The idea of time is a praxeological category.
Action is always directed toward the future; it is essentially and necessarily always a planning and acting for a better future. Its aim is always to render future conditions more satisfactory than they would be without the interference of action. The uneasiness that impels a man to act is caused by a dissatisfaction with expected future conditions as they would probably develop if nothing were done to alter them. In any case action can influence only the future, never the present that with every infinitesimal fraction of a second sinks down into the past. Man becomes conscious of time when he plans to convert a less satisfactory present state into a more satisfactory future state.
For contemplative meditation time is merely duration, "la durée pure, dont l'écoulement est continu, et où l'on passe, par gradations insensibles, d'un etat a l'autre: Continuité réellement vécue."  The "now" of the present is continually shifted to the past and is retained in the memory only. Reflecting about the past, say the philosophers, man becomes aware of time. However, it is not recollection that conveys to man the categories of change and of time, but the will to improve the conditions of his life.
Time as we measure it by various mechanical devices is always past, and time as the philosophers use this concept is always either past or future. The present is, from these aspects, nothing but an ideal boundary line separating the past from the future. But from the praxeological aspect there is between the past and the future a real extended present. Action is as such in the real present because it utilizes the instant and thus embodies its reality. Later retrospective [p. 101]reflection discerns in the instant passed away first of all the action and the conditions which it offered to action. That which can no longer be done or consumed because the opportunity for it has passed away, contrasts the past with the present. That which cannot yet be done or consumed, because the conditions for undertaking it or the time for its ripening have not yet come, contrasts the future with the past. The present offers to acting opportunities and tasks for which it was hitherto too early and for which it will be hereafter too late.
The present qua duration is the continuation of the conditions and opportunities given for acting. Every kind of action requires special conditions to which it must be adjusted with regard to the aims sought. The concept of the present is therefore different for various fields of action. It has no reference whatever to the various methods of measuring the passing of time by spatial movements. The present encloses as much of the time passed away as still is actual, i.e., of importance for acting. The present contrasts itself, according to the various actions one has in view, with the Middle Ages, with the nineteenth century, with the past year, month, or day, but no less with the hour, minute, or second just passed away. If a man says: Nowadays Zeus is no longer worshipped, he has a present in mind other than that the motorcar driver who thinks: Now it is still too early to turn.
As the future is uncertain it always remains undecided and vague how much of it we can consider as now and present. If a man had said in 1913: At present--now--in Europe freedom of thought is undisputed, he would have not foreseen that this present would very soon be a past.
 Henri Bergson, Matière et mémoire (7th ed. Paris, 1911), p. 205
 Edmund Husserl, "Vorlesungen zur Phänomenologie des inneren Zeitbewusstseins," Jahrbuch Fü Philosophie und Phänomenologische Forschung, IX (1928), 391ff.; A. Schütz, loc cit., pp. 45 ff.
 "Ce que j'appelle mon présent, c'est mon attitute vis-à-vix de l'avenir immédiat, c'est action imminente." Bergson, op. cit., p. 152.