PHYSICS. of the eye upwards, downwards, to the right-hand, to the left, and to various oblique pofitions; and the feveral coats and humours that make up the organ, have not only their magnitude, figure, confiftence, fituation, and connexion, admirably adapted to that end; but the tranfparency of the cornea, and the three humours, the opacity of the uvca, the femi-opacity of the retina, and the feveral motions of the parts of the eye, which are requifite to receive, tranfmit, refract, and difpofe the vifual rays, that come from the object, after the manner neceffary to make the liveliest picture of it in the bottom of the eye; wonderfully confpire to compleat this matchlefs inftrument of vifion : whence we may as properly conclude, that an eye, as that a telescope, is made to view objects with. But, in that admirable perforation of the uvea, which we call the pupil, nature has greatly exceeded art. For tho' we are obliged to employ opake bodies, with feveral circular apertures, to the object-glaffes of telescopes, that fome may let in lefs light, and others more, according as the objects require to be illumin'd; that part of the uvea, which is fufpended in the aqueous humour, is an aperture that widens and contracts it felf, in an inftant, according to the exigency of the object.

But for the ufes of the feveral parts of the eye, I refer my reader to Scheiner's Oculus, and Des Cartes's Dioptrics; whence it will appear, that, in forming this part, nature not only acted with defign, but with fo great skill in optics, that a more than ordinary acquaintance with that science is neceffary to understand the wifdom of the feveral contrivances; which, perhaps, no degree of skill whatever in it, would enable a man to alter for the better.

'Twere tedious to mention other parts of the body, that manifeftly appear to have been ordain'd to certain ufes. The books of anatomifts are full of paffages to this purpose of which I fhall only fay in general, that tho' what they deliver is fufficient to fhew all the parts of the body to be the effects of an intelligent caufe; yet, unless their defcriptions, and reflections, be improved by mathematics, mechanics, and chymistry, we fhall have but an imperfect notion how intelligent that caufe is; or how much wifdom is difplay'd in the ftructure of a human body, and its feveral parts.

I know 'tis objected, by the Epicureans, that the parts of animals were firft made, and their ufes afterwards difcover'd, by the fagacity of men. But this is a fophiftical objection. For, firft, many of the internal parts perform their functions, without our having any knowledge of their struEture, or fituation; fo far are they from being applied to fuch ufes by our fagacity. And as for the limbs, and other parts, which we move at pleafure, 'tis true, they cannot be employ'd to their refpective ufes, till actually form'd; neverthelefs, they might be originally fo form'd, as, in due time, to be fit for fuch ufes. And, in effect, we fee that a chick is furnish'd with compleat eyes and wings, before it be hatch'd; tho' whilst inclofed in the egg, it can make no ufe of them, either to fee, or fly. And why was it, do the Epicureans think, that nature provided a whole fett of temporary

temporary parts for pregnant females, and animals in the womb; which, PHYSICS. when they are come into a freer ftate, partly fhrink away of themfelves, and partly turn to a ligament, fitted no longer for theformer, but for a more feafonable ufe? And 'tis to be noted, that thefe umbilical veffels, and the placenta to which they are faften'd, is of no neceffity or use to the female before conception; and therefore, thofe temporary parts, appear to have been defign'd by nature for the propagation of the fpecies.

And tho' the fagacity of men, may have found out fome ufes of the particular parts of their bodies, which feem not to have been primarily intended by the author of nature; yet this does not prove, that thofe ufes were undefign'd: for the prefcience, and goodness of God, are fufficient to render it probable, that he who gave man both the limbs of his body, and the endowments of his mind, did both foresee what ufes men might, according to their fagacities, and emergencies, make of thefe parts; and fo contrive the parts, that they fhould be applicable to fuch ufes.

And, we may now proceed to the latter part of our propofition; which afferts, that, in fome cafes, from the known ends of nature, as well as from the ftructure of the parts, probable conjectures may be form'd about the particular offices of them.

This could not have been feasonably fpoken to before; because the arguments that were founded on the ufes of the parts of animals, fuppofe thofe parts to have been deftin'd to particular uses, knowable by us; and that the feveral parts of the body were contrived as wifely, and commodiously, as men are able to devife, in order to the ends of nature: which muft always be understood to have united in her defigns, the ufes of the parts, and the welfare of the whole.

And, indeed, if we confider how admirable a fitness there is in the parts of a human body, to thofe particular ends we can difcover them to have been defign'd for; it feems allowable to conjecture, that such a part was not primarily defign'd to fuch an ufe, if it is, on the account of its ftructure, or otherwife, lefs fitted for it than the conftant wifdom of nature feems to require; efpecially if there be any other parts, by which the office may be more commodiously performed. And, on the other fide, it feems probable, that fuch a part was deftin'd to fuch an use, if the use itself appear to be neceffary, and the part better fitted for it than any other.

Thus, tho' anatomical and optical writers, for many ages, unanimously concluded, the cryftalline humour to be the principal feat of vision; yet the industrious Scheiner juftly rejects that receiv'd opinion, upon fhewing, that it fuits not with the skill and providence of nature, that it fhould be fo, fince it wants many requifite qualifications for that purpofe; and efpecially fince most of thefe are to be found in the retina. And, I remember, upon asking our famous Harvey, what induced him to think of a circulation of the blood; he faid, that obferving the valves in the veins of many parts of the body, fo placed, as to give free paffage to the blood towards the heart; but to oppofe the paffage of the venal blood, the contrary way; he

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imagin'd

PHYSICS. imagin'd that fo provident a caufe, as nature, had not thus placed fo many valves without design: and as no defign feem'd more probable than that, fince the blood could not well, becaufe of the interpofing valves, be fent by the veins, to the limbs, it should be fent thro' the arteries, and return thro' the veins, whofe valves did not oppofe its course that way.

Thus, tho' the ancient anatomifts, and phyficians, believ'd the parts were nourished by the venal blood; the modern writers teach them to be nourifhed by the blood, in its paffage thro' the arteries. Not that they think the blood, which runs thro' the veins, altogether unfit to fupply the parts with that vital liquor; but because they judge the veins to be lefs fit for this purpofe, than the arteries; into the latter whereof the blood comes immediately from the left ventricle of the heart, agitated, and fpirituous, and, by a brisk impulfe, better fuited to anfwer this end. But the writings of phyficians, and anatomifts, being filled with inftances of this kind, I forbear to mention any more.

PROP. III.

It is rational, from the manifeft fitness of fome things, to cofmical, or animal ends, to infer, that they were thereto ordained by an intelligent agent.

Care feems to have been taken, that the body of an animal fhould be provided not only with all things that are ordinarily neceffary, and convenient; but with fome fuper-abundant provifion against accidents. Thus, tho' a man may live, and propagate his fpecies, after the loss of an eye; yet nature furnishes us with two, that, in cafe one be destroy'd, the other may fuffice for vifion. And the like may be faid of the ears. In fhort, nature has furnish'd men with double parts of the fame kind, where it is highly useful, and may be permitted, without prejudice, to the reft of the body. And this is the more confiderable, because, in other parts, nature appears to husband things fo, as to avoid doing what is fuperfluous. Thus, within the skull, fome veffels, that would, in other parts of the body, have double coats, are very thin; the skull being ordinarily fufficient to defend them from external injuries.

Another argument, that nature acts with defign, about animals, may be drawn from what anatomifts obferve of thofe parts of the womb, or the fœtus, that are to be found but at certain times, when there is need of them; and not at others, when they would be ufelefs. Thus, when a woman is with child, the Vafa umbilicalia are produced to be canals, either for the blood, or alimental juice, and fpirits, that then ought to pafs between the womb and the foetus, by means of the placenta. And tho', as long as the child continues in the womb, thefe temporary parts continue with him; yet, as foon as he comes into the world, the umbilical veffels, particularly the two arteries, and the vein, together with the membranes they are wrapp'd up in, with the chorion, and the amnios, that involve the foetus, are thrown off, as unneceffary, and expell'd in the after-birth; there remaining only that part of the umbilical vessels that

lies within the child's abdomen, between the navel and the liver; where PHYSICS. its ufe is confiderable, tho' new; for it ferves now no longer to convey blood, or an alimental liquor, to and fro, but degenerates into a liga

ment.

Thus, alfo, the Foramen ovale, gives paffage to the blood from the right ventricle of the heart to the left, that the circulation of it may be maintain'd; for it cannot in the embryo, as in a born child, pass thro' the veffels of the lungs, from one of the ventricles to the other: whence this contrivance feems to be an expedient that nature employs, till the fœtus is excluded; when that temporary conformation is obliterated. For the child, now breathing the free air, is in a condition to make the blood circulate thro' the pulmonic veffels, according to the primary intention of nature. From which, and the like inftances, we may infer, that thefe temporary parts were framed by a fore-knowing, as well as a defigning agent; who intended they fhould ferve for fuch a purpofe, and then be laid afide: for 'tis uttterly improbable, that an undefigning agent fhould fo appofitely, and exquifitely, frame fcaffolds for a future building, if he did not, before-hand, deftine both the one and the other, to concur to the fame ultimate effect.

Another argument, for our prefent purpose, may be drawn from the confideration of what, in animals, is commonly call'd inftinct: which, in fome cafes, more directly regards the welfare of the creature; in others, the propagation of the fpecies; and, fometimes again, refpects both. The writers of voyages, and natural hiftory, recount ftrange inftances of the inftinct obfervable in certain animals. But we need not lay the stress of our argument upon dubious, or fufpected relations; fince what I have met with, in authors of good authority, or receiv'd from the mouths of credible travellers, may ferve my prefent turn; especially, if we may take the word inftinct in a latitude, fo as to comprize thofe untaught methods, and expedients, that are made ufe of by fome animals, to avoid dangers, provide for their future neceffities, or to catch their prey.

Surprizing things are related, not only by poets, but by more credible writers, about the fagacity and government of bees; in point, both of œconomy, and politics. But tho' I fhall not build any thing upon fufpected authorities, yet, having long kept a transparent hive, and thereby gained the opportunity to make frequent obfervations of the actions of thefe little animals; I confefs, I difcover'd fome things that I did not believe before which induced me to look upon them, as very fit inftances of creatures endow'd with natural instinct and providence. For, 'twere hard for a mathematician, in contriving fo many cells as bees make in the area of one of their combs, to husband fo little space more skilfully than these animals. And they not only carefully, and feafonably, lay up their honey, to ferve them all the winter; but, curiously, clofe the particular cells with covers of wax, that keep the included liquor from fpilling, and from external injuries. I do not here mention the prognoftication of weather that may be made in the morning, by their keeping within their

hives,

PHYSICS. hives, or flying early abroad, to furnish themselves with wax, or honey; or, by their unexpected return before a ftorm: becaufe, I fufpect, that these things are not fo much the effects of inftinct, as of a tenderness, and quickness of fenfe; fomething analogous whereto, may be feen in a good weather-glafs; and is, alfo, to be found in many wounded, and valetudinary perfons, who are affected with fuch beginning alterations in the air, as other men perceive not. But, among the peculiarities to be obferv'd in the conduct of bees; 'tis very remarkable, that, after a fight, they take up the dead which lay on the ground, and, as I have obferv'd, fly away with them far from their hive.

Another obvious inftance of the inftinct that nature has given to fome defpicable infects, may be taken from ants. For, 'tis known, that these little creatures do, in the fummer, hoard up grains of corn against the winter. And their fagacity is the more confiderable, if it be true, what many learned men affirm, that they eat off the germen of the grains they lay up, left the moisture of the earth, expofed to the rains, fhould make them fprout. But, whatever become of this tradition, thefe infects perform fome other actions, greatly refembling thofe proceeding from fagacity and industry.

The natural skill of fpiders, in weaving their webs, that are so fitly contrived, both to catch their prey, and give them immediate notice of its being caught, is a thing which, if it were not familiar, would be look'd upon as admirable. And this skill is not, as fome imagine, an effect of imitating their parents; for if the eggs be taken away, and enclosed in a glafs; when they come to be hatch'd by the heat of the fun, the little creatures will, immediately, fall to fpinning in the glafs itself; as was related to me by an eminent mathematician, who made the experiment. And I faw the lefs reafon to diftruft it, becaufe having, by an external heat, hatch'd many eggs of filk-worms, in a place where there had not been any of a long time before, nor, probably, ever, till then; yet the worms, produced by thefe eggs, did, in autumn, of their own accord, climb up to fuch convenient places as I had prepared for them, and there weave those curious oval prifons, wherein they enclose themselves, and which are unravel'd into extremely fine filk.

But this provident industry is not confined to infects, for 'tis to be found in many of the greater animals; particularly in the beaver; a creature whereof, indeed, many fabulous ftories are related: yet fober, and judicious perfons, who were either born, or lived in New-England, where these animals abound, have affured me, that the beavers, with their fharp teeth, cut pieces of wood, and fit them to their purpofe; that, by joining their labours, they lay thefe together, fo as to build themselves ftrong winter-houfes; in which there is, fometimes, a kind of fecond ftory for the inhabitants to retire to, when the water chances to overflow; that, for thefe houfes, they chufe a very convenient fituation, juft by fome river, or other water, that can furnish them with fish; and that the hole belonging to each houfe, is placed juft by the water, that

they