602 CEITICAL NOTICES: The extremely suggestive speculations of this last work of Prof. Delboeuf have their foundation partly in the psychological conclusions of his immediately preceding work, Le Sommeil et les Reves (reviewed by Mr. Sully in MIND No. 45), partly in his psycho- physical theories. His physical and his psychological ideas find their point of union in the general doctrine stated in the first chapter of the present essay. In opposition to the prevailing "philosophy of men of science" that starts with lifeless atoms and regards life and mind as the result of their combination, the author assumes that life is coeval with the universe, and that the lifeless can only be explained from the living. Inorganic matter and its "fatal" actions are a "residue" of "vital," "intelli- gent," "free" actions. All the matter of the universe was primitively vital; and "intelligence is the true demiurgus" ; for it is by the free action of intelligence that the transformation of living into dead matter is retarded. We know what it is to be alive, but we do not know what it is to be dead. It is death, therefore, not life, that needs explana- tion. The explanation is to be sought in a study of the processes of nutrition, generation and birth. From the study of nutrition we may perhaps learn what distinguishes living from not-living matter, and how one is transformed into the other. And the problem of death is bound up with the problems of birth and generation ; for death implies birth, though birth does not imply death. That which has had a beginning will not necessarily have an end, but that which has an end must have had a beginning. In his chemico-physiological study of nutrition, which, as he says, in its positive part merely summarises (but in a very lumi- nous and interesting way) the results of science, the author arrives at the general conclusion that living matter is "relatively un- stable," dead matter " relatively stable ". " Food " is defined as " a substance which, introduced into the organism, divides itself into two parts: one, more unstable, which is assimilated; the other, more stable, of which a part is deposited, for example, in shells, teguments, the skeleton, &c,, and of which the other part is eliminated". The "unstable" part is that which retains most " potential energy ". The transformation of " stable " matter into "unstable that takes place during the assimilation of food is necessary because, during the activity of the organism, forces are constantly becoming "fixed," and with this " fixation of force" goes "the stabilisation of matter". Psychologically, what corre- sponds to " fixed " force or " stabilised " matter is the definitely organised portion of the mental life, the perceptions that have become memories of the past, the acts of will that have become organised into habit. In the nervous system there is a stable portion that has been already utilised and an unstable portion that is still disposable. The tendency is to greater " stabilisa- tion". Nutrition cannot continue for ever to replace the lost potentialities of change. Thus there arrives a time when the
