Hegel, Encyclopaedia of the Philosophical Sciences:
We ought, says Kant, to become acquainted with the instrument, before we undertake the work for which it is to be employed; for if the instrument be insufficient, all our trouble will be spent in vain. The plausibility of this suggestion has won for it general assent and admiration; the result of which has been to withdraw cognition from an interest in its objects and absorption in the study of them, and to direct it back upon itself; and so turn it to a question of form. Unless we wish to be deceived by words, it is easy to see what this amounts to. In the case of other instruments, we can try and criticise them in other ways than by setting about the special work for which they are destined. But the examination of knowledge can only be carried out by an act of knowledge. To examine this so-called instrument is the same thing as to know it. But to seek to know before we know is as absurd as the wise resolution of Scholasticus, not to venture into the water until he had learned to swim.