What he formally rejects, is the finality understood in the theological or metaphysical manner: _Cœli enarrant gloriam Dei_. He does not admit that we can “explain” the natural order by a supernatural wisdom. But he in no way contests the finality which Kant called internal. This finality, or better, this reciprocal causality appears in living beings, where the whole and the parts are reciprocally end and means. The tree could not subsist without the leaves any more than the leaves without the tree. Comte expresses this idea in terms which are almost identical with those of Kant, although he did not know them. “We shall,” he says, “cease defining a living being by the collection of its organs, as if these could exist isolated.... In biology the general notion of the being, always precedes that of any of its parts whatever. In sociology, where partial interdependence is less intimate although wider, it would be a serious heresy to define humanity by man ... _a fortiori_ in biology we ought not to conceive the whole from its parts.”[61] As soon as we rise above the inorganic world, the first condition for the study of phenomena is the idea of their consensus, first in biology, and then in sociology. This _consensus_ corresponds to Kant’s internal finality. But the distinction between internal finality and external finality cannot be strictly maintained. We will never affirm that some beings were made in view of others. This would be in the highest degree a theological “explanation” of the first order. But from the positive point of view, we observe that, in order to subsist, organisms need not only special intimate structure, but further require a certain equilibrium of external conditions. At each moment their existence depends at once on their constitution and on the “milieu.” This word, which was destined to attain such popularity and the theory of the “milieu” which Taine has rendered no less popular, belong to Comte. Undoubtedly, the idea was suggested to him, on the one hand by Montesquieu and by his successors, and on the other by the labours of Lamarck and of the contemporary biologists. He also drew inspiration from Bichat’s celebrated _Recherches sur la vie et la mort_. But Bichat especially insisted upon the antagonism between the living being and the forces of the inorganic world which press upon him from all sides. Comte thinks, on the contrary, that the very existence of living beings is the proof of a sufficient harmony between their organism and the milieu. And what we cannot dispute is his merit in having generalised the idea specially applied by Montesquieu to social facts, and also specially applied by Lamarck and Bichat to the phenomena of life.