In these cases, the memory of the facts is connected with that of the atoms which register it; this memory can only be recalled by coming into contact with these atoms.[255] There is also another memory, midway between the unconscious memory of atoms and the conscious memory of the human soul; that of the forms of the various sub-human kingdoms. It is only slightly conscious, for it is not individualised; all the same, it is precise in its nature. It dwells in the vital essence of the form, an essence taken from a collective "block" which supplies a portion of its substance to the individuals of the same species; this incarnate portion of essence, when the form disintegrates at death, returns to the parent "block," to which it communicates the result of its experiences, and when the latter sends out a portion of itself, into a new form, this tentacle, which is, so to speak, the soul of the form, is in possession of the whole of the experiences of the "block."[256] This explains how it is that the individual members of certain hostile species know one another from birth--the chicken, for instance, which, immediately it has left the egg, trembles before the hawk hovering above in the air; such is also the reason why a duckling plunges into water as soon as it comes to a pond, and the same instinct impels a bird to leave its nest and trust itself to the air when fully fledged. In these collective souls, belonging to the mineral, vegetable, and animal kingdoms, there can be recovered the past to which they bore witness, when the atoms of their bodies have been dispersed and entered into new combinations. When the elemental Essence[257] has definitely split up, and the "blocks" have become separate, individualised, human fragments,[258] each of these fragments is a causal body, a definite, immortal _centre_ in the total Centre. Consequently there are in man three kinds of memory: atomic memory, that of the atoms of his bodies; instinctive memory of the special elemental essences which are the collective souls of his various vehicles; and finally, the individual memory of the centre,[259] which is one with the total Centre from which it comes. This element of unity, this human "I" in the divine "I," when sufficiently developed, is able to evoke the memory of all the events in which it has participated in the causal body, and also the memory of those it has witnessed as a collective soul (elemental "block") in bygone ages when active in various mineral, vegetable, and animal species. As a centre in the great Centre, it can also call forth the memory of everything in the Universe that its consciousness can grasp.[260] And when, in this long pilgrimage, it has developed to the farthest limits of the Universe it knows all that has been, is now, and is to be in this Universe, consequently it knows both what it has and what it has not participated in, for everything in the Universe has then become part of itself.