Scientific thought, again, preserves the same habits and the same preferences. It seeks only what repeats, what can be counted. Everywhere, when it theorises, it tends to establish static relations between composing unities which form a homogeneous and disconnected multiplicity. Its very instruments bias it in that direction. The apparatus of the laboratory really grasps nothing but arrangement and coincidence; in a word, states not transitions. Even in cases of contrary appearance, for example, when we determine a weight by observing the oscillation of a balance and not its rest, we are interested in regular recurrence, in a symmetry, in something therefore which is of the nature of an equilibrium and a fixity all the same. The reason of it is that science, like common-sense, although in a manner a little different, aims only in actual fact at obtaining finished and workable results. Let us imagine reality under the figure of a curve, a rhythmic succession of phases of which our concepts mark so many tangents. There is contact at one point, but at one point only. Thus our logic is valid as infinitesimal analysis, just as the geometry of the straight line allows us to define each state of curve. It is thus, for example, that vitality maintains a relation of momentary tangency to the physico-chemical structure. If we study this relation and analogous relations, this fact remains indisputably legitimate. Let us not think, however, that such a study, even when repeated in as many points as we wish, can ever suffice. We must afterwards by genuine integration attain moving continuity. That is exactly the task represented by the return to intuition, with its proper instrument, the dynamic scheme. From this tangential point of view we try to grasp the genesis of the curve as envelope, or rather, and better still, the birth of successive tangents as instantaneous directions. Speaking non-metaphorically, we cling to genetic methods of conceptualisation and proceed from the generating principle to its conceptual derivatives.