If we ask the school philosophers, how the nutritious juice which is ponderous, rises spontaneously to the very uppermost leaves of the highest trees, they will tell us that it rises by attraction. And what is this, but placing us in the same state of doubt and difficulty, with respect to the most common work of vegetation, that we remain in, with respect to the motion of the iron to the load-stone? Both the one and the other are called attraction, but we are equally ignorant, why, or how, the highest leaves of a tree attract the juice which rises from the bowels of the earth, as we are, why or how the load-stone attracts the iron. LXXXIV. Let us proceed to the second mystery. Who can explain to me, the manner in which a juice that is so exceedingly fluid, subtil, and fine, as to be able to circulate through the smallest channels of the fibres, is afterwards converted into the solidity of wood or grain; and this difficulty will increase, if we cast our eyes on the other mixtures, and reflect, that from another juice, or rather most fluid vapour, is generated copper and marble. Aristotle had certainly some reason for saying, that nature was the very devil: _Natura dæmonia est, non divina_ (Lib. de Præsens. per somnum); for by observing her works with attention, it seems as if she did every thing by enchantment. SECT. XXII. LXXXV. It would be even some consolation to us under our ignorance, if only the manner, in which nature works in the interior part of her operations, was hidden from our eyes; but the most humiliating circumstance is, that it is the same, with respect to every thing that immediately presents itself to our senses. Bodies are familiar to our touch; but hitherto, we have not been able to discover, whether they are composed of indivisible points, or of parts infinitely divisible; nor to what it is owing, that one body is hard, and another soft, one solid, another fluid, one opake, and another diaphanous. We are continually viewing colours; but we do not yet know, what sort of things colours are; whether they are mere reflexions of the light, or whether they are intrinsic accidents appertaining to the object. The light illuminates, and assists us to see; but we find our understandings greatly obscured, when we consider the nature of light. Whether we conceive it to be substance, accident, body, or spirit, none of them are applicable to its nature, and still they all seem to be so. And with how many impenetrable doubts and difficulties are we surrounded, when we consider the species which we call visible? If there is any one difficulty superior to, or any one inequality more striking than another in the mysteries of physics, I will venture to pronounce this is it. How the visible species of a star in the firmament, can in an instant, be translated from the same star to our eyes, when it must travel in that instant many thousands of miles, is beyond conception; as is likewise, how this species can exist at one and