[399] Cf. the words in the Preface to _Matter and Memory_: “_The whole personality, which, normally narrowed down by action, expands with the unscrewing of the vice in which it has allowed itself to be squeezed_,” or the words in the same place about the task of metaphysics being the attempt of the “_mind striving to transcend the conditions of useful action_.” [400] We refer elsewhere in this chapter to Bergson’s idea that living beings are “centres of indetermination,” that is to say, creatures who hold their place in nature and that of their species by “persisting in their own being” (the language of Spinoza) by acting and reacting upon some of the many forces of nature that act upon them, and by avoiding the action of other forces and other animals. “They allow to pass through them,” he says, “so to speak, those external influences which are indifferent to them; the others isolated become ‘perceptions’ by their very isolation” (_Matter and Memory_, pp. 28, 29). We also refer to Bergson’s idea that the life-force has expressed itself along different grades of being (mineral, animal, and so on). Both these ideas are a partial explanation of what we mean by the presence of a spiritual activity in both inanimate and animate nature. So also is Bergson’s idea that the purely mechanical explanation either of nature or of life is but a device of the intellect for the purposes of description. More specifically it is expressed, too, in his idea that “Our representation of matter is the measure of our possible action upon bodies; it results from the discarding of what has no interest for our needs, or more generally for our functions” (_Matter and Memory_, p. 30), or that “Consciousness” is just this choice of “attaining to” or attending to “certain parts and certain aspects of those parts” of the “material universe” (_ibid._ p. 31), or that “sense-perception” is an “elementary question to my motor activity.” “The truth is that my nervous system, interposed between the objects which affect my body and those which I can influence, is a mere conductor, transmitting, sending back, or inhibiting movement. This conductor is composed of an enormous number of threads which stretch from the periphery to the centre, and from the centre to the periphery. As many threads pass from the periphery to the centre, so many points of space are there able to make an appeal to my will, and to put, so to speak, _an elementary question to my motor activity. Every such question is what is termed a perception_” (_ibid._ 40, 41; italics mine). Or, as he puts it, on p. 313, “No doubt the choice of perception from among images in general is the effect of a _discernment which foreshadows spirit_.... But to touch the reality of spirit we must place ourselves at the _point where an individual consciousness_, continuing and retaining the past in a present enriched by it, _thus escapes the law of necessity_, the law which ordains that the past shall ever follow itself in a present