On the other hand the work is no less to be admired in little than in great: for I find as well in little as in great a kind of infinite that astonishes me. It surpasses my imagination to find in a hand-worm, as one does in an elephant or whale, limbs perfectly well organised; a head, a body, legs, and feet, as distinct and as well formed as those of the biggest animals. There are in every part of those living atoms, muscles, nerves, veins, arteries, blood; and in that blood ramous particles and humours; in these humours some drops that are themselves composed of several particles: nor can one ever stop in the discussion of this infinite composition of so infinite a whole. The microscope discovers to us in every object as it were a thousand other objects that had escaped our notice. But how many other objects are there in every object discovered by the microscope which the microscope itself cannot discover? What should not we see if we could still subtilise and improve more and more the instruments that help out weak and dull sight? Let us supply by our imagination what our eyes are defective in; and let our fancy itself be a kind of microscope, and represent to us in every atom a thousand new and invisible worlds: but it will never be able incessantly to paint to us new discoveries in little bodies; it will be tired, and forced at last to stop, and sink, leaving in the smallest organ of a body a thousand wonders undiscovered. SECT. XXII. Of the Structure or Frame of the Animal. Let us confine ourselves within the animal's machine, which has three things that never can be too much admired: First, it has in it wherewithal to defend itself against those that attack it, in order to destroy it. Secondly, it has a faculty of reviving itself by food. Thirdly, it has wherewithal to perpetuate its species by generation. Let us bestow some considerations on these three things. SECT. XXIII. Of the Instinct of the Animal. Animals are endowed with what is called instinct, both to approach useful and beneficial objects, and to avoid such as may be noxious and destructive to them. Let us not inquire wherein this instinct consists, but content ourselves with matter of fact, without reasoning upon it.