different rules, quite independent of one another according to all appearance, in a single principle, — possess on that account no claim to be teleological grounds of explanation in Physic. Even if they deserve to be brought into consideration in the universal theory of the purposiveness of things of nature, yet they belong to another [science], i.e. Metaphysic, and constitute no internal principle of natural science; as with the empirical laws of natural purposes in organised beings, it is not only permissible but unavoidable to use the teleological mode of judging as a principle of the doctrine of nature in regard to a particular class of its objects.

So to the end that Physic may keep within its own bounds, it abstracts itself entirely from the question, whether natural purposes are