We admit that the life phenomena are attached to physicochemical manifestations, but it is true that the essential is not explained thereby; for no fortuitous coming together of physicochemical phenomena constructs each organism after a plan and a fixed design (which are foreseen in advance) and arouses the admirable subordination and harmonious agreement of the acts of life.... We can only know the material conditions and not the intimate nature of life phenomena. We have therefore only to deal with matter and not with the first causes or the vital force derived therefrom. These causes are inaccessible to us, and if we believe anything else we commit an error and become the dupes of metaphors and take figurative language as real.... Determinism can never be but physicochemical determinism. The vital force and life belong to the metaphysical world. In other words, Bernard thinks it his task to account for individual life phenomena on a purely physicochemical basis--but the harmonious character of the organism as a whole is in his opinion not produced by the same forces and he considers it impossible and hopeless to investigate the “design.” This attitude of Bernard would be incomprehensible were it not for the fact that, when he made these statements, the phenomena of specificity, the physiology of development and regeneration, the Mendelian laws of heredity, the animal tropisms and their bearing on the theory of adaptation were unknown. This explanation of Bernard’s attitude is apparently contradicted by the fact that Driesch[2] and v. Uexküll,[3] both brilliant biologists, occupy today a standpoint not very different from that of Claude Bernard. Driesch assumes that there is an Aristotelian “entelechy” acting as directing guide in each organism; and v. Uexküll suggests a kind of Platonic “idea” as a peculiar characteristic of life which accounts for the purposeful character of the organism.