in the spirit; and to prevent its avolation when excited.

Putrefaction is a mixed operation of the spirit, and grosser parts; for when the spirit, which restrained and held the parts of a body together, is partly discharged and partly rendered languid, all things are dissolved, and return to their heterogeneous principles; for now the spirit contained in the body gathers to itself; the oily parts to themselves; the aqueous also to themselves; and the fæces to themselves; upon which necessarily ensues that cadaverous odour, that unctuosity, sliminess, and confusion of parts observable in putrefaction.*

Generation likewise, or vivification, is a mixed operation of the spirits and grosser parts; but in a quite different manner: for in this case the spirit is totally held in, (but still expands and moves itself,) whilst the grosser parts are not dissolved, but obey the motion of the spirit; whereby they are swelled, and thrust out into various figures whence proceeds generation and organization. And, therefore, vivification is always wrought upon a tenacious, viscous matter, though soft and yielding; fit at once to detain the spirit, and yet gently yield thereto; as the spirit forms

* See the nature of putrefaction, in the Philosophical Transactions; or Boerhaave's Chemistry, Process 88.

its parts. And this appears in the matter of all vegetables and animals, whether generated in putrefaction, or from seed; in all which there manifestly appears a substance which is hard to separate, but easy to yield.

AXIOM IV.

All animate bodies have two kinds of spirits; viz. a lifeless spirit, such as resides in bodies inanimate; and a vital spirit, superadded to it.

EXPLANATION.

We formerly observed, that in order to procure long life, the human body should first be considered as a body inanimate, and unrepairable by aliment; and again, as a body reparable and nourishable: for the former consideration supplies the laws of consumption; and the second the laws of repair. We are, therefore, to understand, that all the parts of the body, the flesh, the bones, the membranes, the organs, &c. have each of them, whilst alive, such spirits diffused through their substance, as are proper to them respectively, when separated, and dead, and such as remain even in the carcass: but the vital spirit, though it presides over, and has a certain agreement with them, is yet a very different thing; as being entire, and subsisting of itself.

There are two principal differences betwixt the lifeless and the vital spirits; the one, that the lifeless spirits are not continued in themselves, but in a manner cut off and surrounded by the gross body that intercepts them; like air mixed in among snow or froth: but all the vital spirit is continued in itself, through certain canals, which it penetrates without being totally intercepted. And this spirit also is of two kinds; the one only branching out, and striking through little tubes, and, as it were, single threads: but the other has also certain cells; so as not only to be continued with itself, but likewise copiously collected, in proportion to the body, into cavities which serve as fountains to numerous rivulets running from them. The principal cells, or cavities, of this kind, are seated in the ventricles of the brain; which in the more ignoble creatures are narrow; so that their spirit seems diffused over the whole body, rather than contained in cells; as appears in serpents, eels, and flies, which, when cut to pieces, long continue moving in all the separated parts even birds continue struggling for a while, after their heads are off; because they have little heads, and little cells of spirits. But the more noble animals have these ventricles still larger; and man the largest of all.*

* Let these axioms and explanations by no means be lightly censured, and rejected as conjectural things; they

The other difference between the spirits is, that the vital spirit has some kind of inflammability, and resembles a breath composed of flame and air; as the juices of animals contain both oil and water. And this kind of inflammability is attended with peculiar properties and motions; for even inflammable smoke is warm, subtile, and moveable, before it catches fire, and turns to flame; yet becomes a different thing when changed to flame. But the kindling of the vital spirits is, by many degrees, more gentle than the softest flame, even that of spirit of wine: and is also largely mixed with an aerial substance, so as to become a peculiar and almost inexplicable union, of a flamy and aerial nature.

AXIOM V.

All the parts of the body have their proper and respective natural actions; but each of them is excited and quickened by the vital spirit.

EXPLANATION.

The actions or functions of any part are correspondent to the nature of that part; such as attraction, retention, digestion, assimilation, separation, excretion, perspiration; and even the

are meant to be deduced from the preceding history, in the strict and genuine way of interpreting nature.

senses themselves, according to the properties of every organ; as the stomach, heart, spleen, brain, ear, eye, &c. Nor could any of these actions be excited and performed without the animating vigour and presence of the vital spirit, and its heat; no more than one piece of iron could attract another, unless first animated by the loadstone; or an egg produce a chick, unless the substance of the hen were first actuated by the treading of the cock.

AXIOM VI.

The lifeless spirits are nearly of the same substance with air; but the vital spirits approach nearer to the substance of flame.

EXPLANATION.

The explanation of the preceding fourth axiom, is also explanatory of this. But hence it is, that all fat and oily substances continue long in their own state; as the air does not greatly operate upon them, nor they themselves greatly incline to mix with the air. But that is an empty conceit which supposes flame to be kindled air; for flame and air are as heterogeneous as oil and water. The sense of the present axiom therefore is, that the vital spirits only approach nearer to the substance of flame than the lifeless

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