it meets with at its entring into the Heart,
which is a full Stop, and an Outlet alter-
nately; fo there must be some fide-way
Veffels out of each into different Sets of
Muscles, upon which these two Forces
muft act oppofitely, or alternately; and
'tis likely there are Outlets out of the
Nerves, through which the Steam iffues,
into each, or between the two, and acts
upon the blood and Juices emitted into
those Muscles, and either expands those
Fluids, or inflates the infinite Numbers of
small bladders, without venting, other-
wife than by the Will, or flowly. Whe-
ther the Muscles are kept-gently extend-
ed with Steam by the Nerves, and the
blood be iffued into it, or they be kept
gently extended by the blood, and the
Steam be iffued into the blood, has not
been clearly obferved.

CHA P. IX.

Voluntary Motion, though not directed, yet perform'd by the fame Agents.

PE

EOPLE afcribe all the voluntary Animal Operations of the body to fomething Spirits and they call animal Spirits, I fuppofe they fame mean infinitely fmall Particles of Matter, thing.

F 4.

fuch

fuch as can in an Inftant pervade the blood, and pafs along the Veffels from one Part to another. I confefs I have no Notion of any other Spirits befides this Steam, which, I fuppofe, confifts of Fire, Spirits, Salt, Air, Water, &c. That Degree of Heat, or the Corpufcles of Fire diffufed at that Distance they are in our bodies, if they did not entangle with the Corpufcles of the Fluids, &c. in our bodies could contribute very little towards the Motion of blood or parts; because they would, immediately in Action, pervade all the Parts of our bodies, if they were much more bulky and folid than they are, and fly off. If the Corpufcles of the Agent, which extends the Muscles, were as small as thofe of Fire, they would pervade the Sides of the Tubes; if as sharp as thofe of Salts, they would wound and cut the Parts, confidering with what vaft Force they are compreffed: but small Maffes compofed of Corpuscles of Fire, adhering to Corpufcles of fine fluids, will pervade the fluids, but neither pervade or wound the Tubes. If other Spirits did fubfift in our bodies, they muft continually have fomething to impell or force them to extend the Muscles in the different Parts of the body: There

any

muft

must be a Part of equal force, to move each other Part, from the Head, or wherever you begin, and a Part there, ftrong enough to move them all, and the last must be moved by a stronger Agent, or move itself; whereas we fee no other Part concerned to move a Finger, but the Mufcles and Parts which belong to it. Befides, confidering those Spirits must be expanded, they muft continually go off in a vast Quantity at the Pores, by the Lungs, &c. and must continually be fupply'd by nearly the fame Quantity; and I believe it will be hard to affign any other Rife from whence they can have their Supply or Impulfe: Allow they were moved from Part to Part, by fome Agent which we cannot comprehend, which they call the Mind or Will, can any one conceive, how Matter fo small and fo volatile, moved fo forcibly, frequently, in all the Parts of our Bodies at once for a long Time, fhould not get off at the Lungs and Pores, when they are fo open by Heat or Action, that even a Cloud flies out vifibly, fufficient to fill all the Space in one of our Bodies in a very short time; nay, even to fill a little clofe Room, fo as almoft to ftifle one. If voluntary Motion, be performed by Steam

iffued

No reafon

iffued out of the Blood, and that Steam go off in fuch Quantity, 'tis neceffary that the Motion of the Blood fhould be fo extremely quick as it is, and that it fhould be quickened in proportion to the Expence of the Steam, which Action fupplies frefh Steam as above.

I fhall not endeavour to attribute any formaking of the Operations of the Mind to Matthe Mind ter; but we find as far as we have yet an Agent. reached, that God has fo ordered Things in the inanimate World, that Matter moves Matter by the natural Qualities wherewith he has endued each Species of it, and by the fhorteft plaineft Ways. And if thefe Agents can move the Blood and Parts of the Body according to the natural Laws of Matter, the Body will appear a more perfect regular Machine, and more fimple. And if the Strength of each Animal be augmented and diminished in Proportion to the Supplies and Expence of this Steam, perhaps it may be poffible to fhew, that this Steam is the Agent which moves the Parts of our Body, as well voluntary as involuntary, and after what Manner it moves them: for I think it will be more eafy to demonftrate how this Steam, which conftantly fills all the Arteries and Nerves,

may

may extend and contract the Muscles, &c. with the Affiftance of the Atmosphere, than any Agent yet affigned. The Obftruction of the Steam in any of the Mufcles, difables them from extending and contracting, and confequently from moving the Part affigned them. When the Steam is too fharp or full of Salts, it wounds the Muscles, and makes them fore, &c. And 'tis likely when they are too moist and precipitate, or are condensed by Cold in the Muscles, they cause Rheumatisms, and Palfies.

has a

rations,

That our Mind has Power to direct The Mind the Operation of all our Parts, to which Power of Providence has given that we call volun-directing tary Motion, is evident; and 'tis alfo evi-our Opedent, that the Force of that Operation, is and what limited in Proportion to the Quantity or Power. Fineness of the Agent, the Freedom or Obstruction it meets with in the Paffages, and the different Contrivance of the Mufcles and Parts upon which it acts, and whether there be any other Share of the Operation performed by the Mind, when it would iffue the Agent, which I fuppofe to be Steam, to one Part, than shutting the Valves or Paffages to other Parts, and permitting that Steam to iffue into the Muscles which are to be contracted,

or