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one of them has, hitherto been, or can be accounted for on principles merely mechanical ; and that nothing could be more vain and imaginary, than to suppose with Descartes, that merely from a circular motion's being impressed by the supreme agent on the particles of extended substance, the whole world with all its several parts, appurtenances, and phænomena might be produced, by a necessary consequence from the laws of mo..
233. Others fuppofe that God did more at the beginning, having then made the feeds of all vegetables and animals, containing their solid or. ganical parts in miniature, the gradual filling and evolution of which, by the influx of proper juices, doth constitute the generation and growth of a living body, So that the artificial structure of plants and animals daily generated, requires no prefent exercise of art to produce it, having been already framed at the origin of the world, which with all its parts hath ever since subsisted going Jike a clock or machine by itself, according to the laws of nature, without the immediate hand of the artist. But how can this hypothesis explain the blended features of different species in mules and other mongrels? or the parts added or changed, and sometimes whole limbs loft by marking in the womb ? or how can it account for the resura' rection of a tree from its stuinp, or the vegetative power in its cutting? in which cases we must necessarily conceive something more than the mere evolution of a feed.
234. Mechanical laws of nature or motion di. rect us how to act, and teach us what to expect. -Where intellect presides, there will be method and order, and therefore rules, which if not stated
and constant would cease to be rules. There is therefore a constancy in things, which is styled the course of nature (a). All the phænomena in nature are produced by motion. There appears an uniform working in things great and small, by attracting and repelling forces. But the particular laws of attraction and repulsion are various. Nor are we concerned at all about the forces, nei, ther can we know or measure them otherwise than by their effects, that is to say, the motions, which motions only, and not the forces, are indeed in the bodies (b). Bodies are moved to or from each other, and this is performed according to different laws. The natural or mechanic philosopher endeavours to discover those laws by experiment and reasoning. But what is said of forces residing in bodies whether attracting or repelling, is to be regarded only as a mathematical hypothesis, and pot as any thing really existing in nature.
235. We are not therefore seriously to suppofe with certain mechanic philosophers, that the midute particles of bodies have real forces or powers by which they act on each other, to produce the various phænomena in nature. The nunute corpuscles are impelled and directed, that is to say, moved to and from each other according to various rules or laws of motion. The laws of gravity, magnetism, and electricity are divers. And it is not known, what other different rules or laws of motion might be established, by the author of nature. Some bodies approach together, others fly asunder, and perhaps some others do neither. When falt of tartar fows per deliquium, it is visi. ble that the particles of water foating in the air
are moved towards the particles of falt, and joined with them. And when we behold vulgar falt not to flow. per deliquium, may we not conclude that the same law of nature and motion doth not obtain between it's particles and those of the floating vapours? A drop of water assumes a round figure, because it's parts are moved towards each other. But the particles of oil and vinegar have no such disposition to unite. And when Aies walk in water without wetting their feet, it is attributed to a repelling force or faculty in the fly's feet, But this is obscure, though the phænomenon be plain.
236. It is not improbable, and seems not unsupported by experiments, that, as in algebra, where positive quantities cease there negative begin, even so in mechanics, where attracting forces cease there repelling forces begin ; or (to express it more properly) where bodies cease to be moved towards, They begin to be moved from each other. This Sir Isaac Newton infers from the production of air and vapours, whose particles fly asunder with such vehement force. We behold iron move towards the loadstone, straws towards amber, heavy bodies towards the earth. The laws of these motions are various. And when it is said, that all the motions and changes in the great world arise from attraction; the elasticity of the air, the motion of water, the descent of heavy, and the ascent of light bodies, being all afcribed to the faine principle; when from insensible attractions of most minute particles ac the smallest distance, are derived cohesion, diffolution, coagulation, animal secretion, fermentation, and all chemical operations; and when it is said, that without such principles there never would have been any motion in the world, and without
the continuance thereof all motion would cease. In all this we know or understand no more, than that bodies are moved according to a certain order, and that they do not move themselves.
237. So likewise, how to explain all those various motions and effects, by the density and elasticity of æther, seems incomprehensible (a). For instance, why should the acid particles draw those of water and repel each other? why should some falts attract vapours in the air, and others not? why should the particles of common falt repell each other, so as not to subside in water? why should the most repellent particles be the most attractive upon contact ? Or why should the repellent begin where the attractive faculty leaves off. These, and numberless other effects seem inexplicable on mechanical principles, or otherwise than by recourse to a mind or fpiritual agent (b). Nor will it suffice from present phænomena and effects, through a chain of natural causes, and subordinate blind agents, to trace a divine intellect as the remote original cause, that first cre. ated the world, and then set it a going. We cannot make even one single step in accounting for the phænomena, without admitting the immediate presence and immediate action of an incorpo. real agent, who connects, moves, and difposes all things, according to such rules, and for such purposes as seem good to him.
238. It is an old opinion adopted by the moderns, that the elements and other natural bodies are changed each into other (C). Now, as the particles of different bodies are agitated by different forces, attracting and repelling, or, to speak more accurateJy, are moved by different laws, how can these forces
(af 153, 162. 133 154, 220. - fc) 148.
or laws be changed, and this change accounted for by an elastic æther? Such a medium, distinct from light or fire, feemeth not to be made out by any proof, nor to be of any use in explaining the phaenomena. But if there be any medium employed, as a subordinate cause or instrument in attraction, it would rather seem to be light (k); since by an experiment of Mr. Boyle's, amber, that hewed no sign of attraction in the shade, being placed where the sun-beams Thone upon it, imme, diately attracted light bodies. Besides, it hath been discovered by sir Isaac Newton, and an admirable discovery it was, that light is an heterogeneous mea dium (1) consisting of particles endued with ori. ginal distinct properties. And upon these, if I may venture to give my conjectures, it seemeth probable the specific properties of bodies, and the force of specific medicines may depend. Different fides of the same ray fhall, one approach and the other recede from the INandic crystal ; can this be account: ed for by the elasticity of a fine medium, or by the general laws of motion, or by any mechanical prin: ciples whatever? And if not, what should hinderi but there may be specific medicines, whose operation depends not upon mechanical principles, how much foever that notion hath been exploded of late years?
239. Why may we not suppose certain idiosyncrasies, sympathies, oppositions, in the solids or fluids or animal spirit of a human body, wich re. gard to the fine insensible parts of minerals or ve getables, impregnated by rays of light of different properties, not depending on the different size, figure, number, folidity or weight of those particles
(1) 152, 156.. (1) 40, 181.