The Metaphysics of Morals by Immanuel Kant Chapter 3 Page 13

freedom and self-legislation of will are both autonomy and, therefore, are reciprocal conceptions, and for this very reason one must not be used to explain the other or give the reason of it, but at most only logical purposes to reduce apparently different notions of the same object to one single concept (as we reduce different fractions of the same value to the lowest terms).

One resource remains to us, namely, to inquire whether we do not occupy different points of view when by means of freedom we think ourselves as causes efficient a priori, and when we form our conception of ourselves from our actions as effects which we see before our eyes.

It is a remark which needs no subtle reflection to make, but which we may assume that even the commonest understanding can make, although