roll through the regions where the stars inhabit; these are lofty and most worthy speculations. From the things, we pass to the Maker, and we glorify God and his greatness. In admiration and incomprehensibility we are indeed lost; but, we are supported by enthusiasm and by gratitude. The excess may be overbearing, but the immediate, if not the ultimate joy, is infinite. As the first and the preparatory measure, therefore, let us in imagination rend from this earth its cities, its towns, and its inhabitants. As one bold and inartificial whole, unstocked with animation, let us contemplate its shape, its nature, and its parts undressed, uncultivated, and unadorned, teeming with various blessings, but still attended with supposed imperfections, let it pass before us in calm and unprejudiced review. The mist of error which too frequently distorts our vision, when we are ourselves as principals concerned, will thus be removed; and we shall, in our speculations, follow the guidance of nature and reason, without being disturbed by those storms of passion, by which human reason is tossed to and fro in the vast ocean of opinion. LET LETTER V. IN the line which I shall lay down, for our future investigations, (for I must still request your permission to postpone them for a short time) I shall endeavour to the utmost of my power, to avoid that extravagant delirium, which too frequently impels men to the creation of visionary systems. Such flimsy fabrics of fancy are too often substituted in the room of plain realities. An attempt to disperse them, is to the irritable mind of their respective builders, as much an object of dread, as if they were not the illusory offspring of the imagination. By us, however, a different path must be pursued. We shall rarely touch upon any thing, but that which we can see ; nor shall we in any instance, I hope, be detected in endeavouring to be thought to see more, than that which has a real existence. It is a truth, however humiliating it may appear, that with all our knowledge, we are in most unequivocal darkness. With infinite faci lity we make worlds; we even compose and string together whole planetary systems; but yet can we say how the common surface of the earth was formed, or how it was furnished with fruits, with pulse, and with that vast variety of nutritious aliment, so providentially supplied for the support of animal life? Can the deepest of our philosophers determine, whether plants were created in their seed, and so dispersed through the elements which had energy to push them into being; or whether they were planted in their pristine soils in the fulness of beauty and maturity? Of the most familiar objects we are in total ignorance. Why then do we idly and presumptuously venture beyond our line? The mind that rushes beyond what experience, or what common sense renders comprehensible, is most indisputably deranged, if not actually insane. Notwithstanding this impenetrable barrier between the creature and the Creator, proud man, full of arrogance and weakness, and in no one instance more conspicuously so, ventures, within the narrow boundaries of his closet, to explain and account for the mighty fabric of the universe, how it was drawn together, and even what what it was at its origin. Thus do philosophers wander in the mazes of error. The compass traces out the geometrician's world; salts fly to the chymist's aid; and to the mineralogist, fire and its raging properties. Each, in a word, interprets the operations of nature, agreeably to the art with which he is the best acquainted. In adverting to circumstances of this nature, the celebrated Boerhaave, not many years ago, conceived it to be useful to lay down certain preestablished data, in palpable and flat contradiction to the opinions at that time fashionable, of destructions, regenerations, and transmutations. He levelled indeed his doctrines chiefly against the alchymists. But, as what he then said, must invariably continue to hold good, I shall give you an idea of it, and, as nearly as possible in his own words. First, he alleges that there are several elementary bodies of such simplicity, that no person can either separate or assign the principles of them. Secondly, That besides the four elements which are known, salt is of the same simplicity, and does not vary otherwise than by its associations with other natures. Thirdly, That metals, quicksilver included, are all of an equal simplicity, entirely different among themselves, themselves, and absolutely different from all the other natural bodies. Fourthly, That pretending to form a metal, with a matter that has nothing metallic in it, by a transmutation of parts, is being as far from truth, as earth from heaven. Fifthly, That such as these bodies are in a large bulk, such they are found again in the smallest parcel. Sixthly, That all impulsions and attractions may blend, and mingle the elementary natures together, vary them by these mixtures, amalgamate, divide, and make them fine so as not to be perceptible; but that all simple natures remain indestructible, and unshaken by any action whatsoever of what is created. Whence it follows, that even chymistry, which employs natural agents, cannot go farther than the force of these agents will admit, and is confined to the uniting or disjoining of natures already made; but can neither destroy what exists, nor change it into what it is not, nor produce a single grain of a new nature. "Chemia adunat vel separat, nec datur tertium facere quod possit." And hence, continues Boerhaave, Newton was mistaken, in thinking that earth could be changed into fire, and Boyle equally so, in supposing it could be changed into water, or that water could be changed into earth. Physics |