It is plain that this is not a principle for the determinant but only for the reflective Judgement; that it is regulative and not constitutive; and that we derive from it a clue by which we consider natural things in reference to an already given ground of determination according to a new law-abiding order; and extend our natural science according to a different principle, viz. that of final causes, but yet without prejudice to the principle of mechanical causality. Furthermore, it is in no wise thus decided, whether anything of which we judge by this principle, is a _designed_ purpose of nature; whether the grass is for the ox or the sheep, or whether these and the other things of nature are here for men. It is well also from this side to consider the things which are unpleasant to us and are contrary to purpose in particular references. Thus, for example, we can say: The vermin that torment men in their clothes, their hair, or their beds, may be, according to a wise appointment of nature, a motive to cleanliness which is in itself an important means for the preservation of health. Or again the mosquitoes and other stinging insects that make the wildernesses of America so oppressive to the savages, may be so many goads to activity for these primitive men, [inducing them] to drain the marshes and bring light into the forests which intercept every breath of air, and in this way, as well as by cultivating the soil, to make their habitations more healthy. The same thing, which appears to men contradictory to nature in its inner organisation, if viewed in this light gives an entertaining, sometimes an instructive, outlook into a teleological order of things, to which, without such a principle, mere physical observation would not lead us by itself. Thus some persons regard the tapeworm as given to the men or animals in whom it resides, as a kind of set-off for some defect in their vital organs; now I would ask if dreams (without which we never sleep, though we seldom remember them) may not be a purposive ordinance of nature? For during the relaxation of all the moving powers of the body, they serve to excite internally the vital organs by the medium of the Imagination and its great activity (which in this state generally rises to the height of affection). During sleep the Imagination commonly is more actively at play when the stomach is overloaded, in which case this excitement is the more necessary. Consequently, then, without this internal power of motion and this fatiguing unrest, on account of which we complain about our dreams (though in fact they are rather remedial), sleep even in a sound state of health would be a complete extinction of life.