the common mother, even then the concept of final causes would only be pushed further back, not eliminated:  the origin of the first organization will always resist mechanical explanation.  Besides this mission of putting limits to causal derivation and of filling the gap in knowledge by a necessary, although subjective, way of looking at things, the Idea of ends has still another, the direct promotion of knowledge from efficient causes through the discovery of new causal problems.  Thus, for example, physiology owes the impulse to the discovery of previously unnoticed mechanical connections (cf. also p. 382 note) to the question concerning the purpose of organs.  As doctrines mechanism and teleology are irreconcilable and impossible; as rules or maxims of inquiry they are compatible, and the one as indispensable as the other.

After the problem of life, which is insoluble by means of the mechanical explanation, has necessitated the application of the concept of ends, the teleological principle must, at least by way of experiment, be extended to the whole of nature.  This consideration culminates in the position that man, as the subject of morality, must be held to be the final aim of the world, for it is only in regard to a moral being that no further inquiry can be raised as to the purpose of its existence.  It also repeats the moral argument for the existence of a supreme reason, thus supplementing physico-theology, which is inadequate to the demonstration of one absolutely perfect Deity; so that the third Critique, like the two preceding, concludes with the Idea of God as an object of practical faith.

* * * * *

There are three original and pregnant pairs of thoughts which cause Kant’s name to shine in the philosophical sky as a star of the first magnitude:  the demand for a critique of knowledge and the proof of a priori forms of knowledge; the moral autonomy and the categorical imperative; the regulative validity of the Ideas of reason and the practical knowledge of the transcendent world.  No philosophical theory, no scientific hypothesis can henceforth avoid the duty of examining the value and legitimacy of its conclusions, as to whether they keep within the limits of the competency of human reason; whether Kant’s determination of the origin and the limits of knowledge may count on continued favor or not, the fundamental critical idea, that reflection upon the nature and range of our cognitive faculty is indispensable, retains its validity for all cases and makes an end of all philosophizing at random.[1] No ethical system will with impunity pass by the autonomous legislation of reason and the unconditional imperative (the admonition of conscience translated into conceptual language):  the nature and worth of moral will will be everywhere sought in vain if they are not recognized where Kant has found them—­in the unselfish disposition, in that maxim which is fitted to become a general law for all rational beings.  The doctrine of the Ideas, finally, reveals to us, beyond the daylight of phenomenal knowledge, the starlit landscape of another mode of looking at things,[2] in which satisfaction is afforded for the hitherto unmet wishes of the heart and demands of the reason.