before it takes this step, must proceed with caution, and not try to explain teleologically every Technic of nature, i.e. every productive faculty of nature which displays in itself (as in regular bodies) purposiveness of figure to our mere apprehension; but must always regard such as so far mechanically possible.

But on that account to wish entirely to exclude the teleological principle, and to follow simple mechanism only — in cases where, in the rational investigation of the possibility of natural forms through their causes, purposiveness shows itself quite undeniably as the reference to a different kind of causality — to do this must make Reason fantastic, and send it wandering among chimeras of unthinkable natural faculties; just as a mere teleological mode of explanation which takes no