Which how they are able to do, will not seem strange, if we consider, first, how little body there is in one of these creatures compar’d to their superficies, or outside, their thickness, perhaps, oftentimes, not amounting to the hundredth part of an Inch: Next, the strength and agility of these creatures compar’d to their bulk, being, proportionable to their bulk, perhaps, an hundred times stronger then an Horse or Man. And thirdly, if we consider that Nature does always appropriate the instruments, so as they are the most fit and convenient to perform their offices, and the most simple and plain that possibly can be; this we may see further verify’d also in the foot of a Louse which is very much differing from those I have been describing, but more convenient and necessary for the place of its habitation, each of his leggs being footed with a couple of small claws which he can open or shut at pleasure, shap’d almost like the claws of a Lobster or Crab, but with appropriated contrivances for his peculiar use, which being to move its body to and fro upon the hairs of the creature it inhabits, Nature has furnish’d one of its claws with joints, almost like the joints of a man’s fingers, so as thereby it is able to encompass or grasp a hair as firmly as a man can a stick or rope. Nor, is there a less admirable and wonderfull _Mechanism_ in the foot of a Spider, whereby he is able to spin, weave, and climb, or run on his curious transparent clew, of which I shall say more in the description of that Animal. And to conclude, we shall in all things find, that Nature does not onely work Mechanically, but by such excellent and most compendious, as well as stupendious contrivances, that it were impossible for all the reason in the world to find out any contrivance to do the same thing that should have more convenient properties. And can any be so sottish, as to think all those things the productions of chance? Certainly, either their Ratiocination must be extremely depraved, or they did never attentively consider and contemplate the Works of the Al-mighty. * * * * * Observ. XXXVIII. _Of the Structure and motion of the Wings of _Flies_._