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1. OUt of what has been said, it may evidently be concluded that, since the Heart is mov'd natu∣rally and, by its motion, presses out a fu∣my humour, which they use to call the Spirit, into the Channels connected with
it self and into the bodies joyn'd to it: and the Flesh is fibrous, viz. certain parts constipated together of a world of minu∣test fibres sticking to one another: and since, if a connaturall moisture, especially being warm, get into such a body, it makes it swell and, of thin, become thicker, of long, shorter: It comes to passe that the Members, whether consisting of such fi∣bres or knit together by them, attain some kind of locall Motion, by that irrigation from the Heart.
2. Again, the Channels, especially if they are extremely little, will swell, too, and become shorter.
3. Since, therefore, 'tis apparent, that there flow abundance of Spirits from the Heart to the Brain; and again, that, from the Brain through the whole body, most∣subtilly-hollow nerves are extended to all the members, and lose themselves by their dispersion, as it were, in the Muscles: 'Tis plain, the Muscles will swell with these spi∣rits, as oft as the Heart overflows; and consequently, become shorter, and the parts adhering to them be drawn back∣wards to the head of the Muscles; and, which clearly follows, all the extremities of the body be mov'd, from the motion of
the Heart, according to what is convenient to its nature.
4. It follows, too, how certain other members, which have no Nerves but only fibres, have motions of their own; which consist almost in nothing else but in con∣traction and dilatation: For, the fibres being made shorter by their irrigation, they draw the body with them into that fi∣gure which follows out of their contracti∣on; which, when the fibres are trans∣vers'd, is dilatation, when other ways set, contraction.
5. Again, hence appears how the pro∣gressive motion of an Animal is effected: For, an Animal which is mov'd by walk∣ing, whilst it stands still, has the Centre of its gravity set directly to the Centre; but, when it sets a foot any way, it inclines the centre of its gravity, and consequently its whole body, that way; till, transferring the other foot, it sets it down too: and this often repeated is walking.
6. But, one that leaps, when he has contra∣cted the superiour or fore-parts to the in∣feriour or hinder-parts; suddenly pouring out spirits through convenient Nerves, he thrusts the fore-parts forwards, with such a force that the hinder-parts follow them.
7. Something like this is the creeping of feetlesse Creatures: for, fixing their breast or some other part, they bow their back∣bone or that which serv's in stead of it, and so draw the hinder to the fore-parts; then, fixing some of their hinder-parts to the Earth, they advance their fore-parts, by straightning again their back.
8. Swimming is made out of leaping: for, it being effected by the Instrument's first being crook'ned and then straight∣ned again; by the resisting Water the bo∣dy is pusht forward: and, the same hap∣pens in flying.
9. Now, the body being heavier then the Medium in a certain proportion, and consequently, obliged to spend a certain time in descending; and the adventitious Motion making the Medium strain with more vehemence against that motion of the body downwards, or according to the centre of its gravity: 'tis plain, such a bo∣dy will not sink.