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RULE VII. The spirit has two desires ; one of multiplying itself, the other of going forth and congregating with its connaturals.
This rule is understood of the lifeless spirits. For with regard to the second desire, the vital spirit has a special abhorrence of leaving the body, seeing it has no connaturals near at hand. It may, perhaps, rush to the extremities of the body, to meet something that it loves, but, as I said before, it is loth to go forth. But the lifeless spirits, on the other hand, are possessed by both these desires. For as to the former, every spirit seated amongst the grosser parts dwells unhappily; and being in such solitude, where it finds nothing like itself, it the more strives to make and create something similar ; and to increase its quantity, it works hard to multiply itself, and prey upon the volatile part of the
With regard to the second desire, namely, that of escaping and resolving itself into air, it is certain that all thin bodies (which are always movable) move willingly to their likes when near at hand. One drop of water moves towards another, and flame to flame; but much more does this appear in the escape of the spirit into the external air, because it is not carried to a particle like itself, but to a very world of connaturals. In the meantime, it should be noted that the going forth and escape of the spirit into the air is a double action, arising partly from the appetite of the spirit, and partly from the appetite of the air ; for the common air is a needy thing, and seizes every
thing with avidity, as spirits, odours, rays, sounds, and the like.
RULE VIII. Spirit detained, if it have no means of generating other spirit, softens likewise the grosser parts.
Generation of new spirit does not take place except upon things which are in a degree near to spirit, as moist bodies are. If therefore the grosser parts wherein the spirit works are in a degree remote, the spirit, though it cannot convert them, yet does all it can to weaken, soften, and disperse them ; so that though it cannot increase its quantity, it may nevertheless live more freely, and amidst things that are better disposed to it. But this aphorism is very useful to our end, because it tends to the inteneration of the hard and stubborn parts of the body by the detention of the spirit.
RULE IX. The inteneration of the harder parts proceeds well when the spirit neither escapes nor generates.
This rule solves the knot and difficulty in the operation of softening the body by the detention of the spirit. For if the spirit when detained in the body preys upon all things within, nothing is gained towards the inteneration of the parts in their substance, but they are rather wasted and corrupted. The spirits therefore besides being detained should be cooled and confined, that they be not too active.
RULE X. The heat of the spirit, to keep the body fresh, should be robust, but not eager.
This rule likewise relates to the solution of the abovementioned difficulty, but it extends much further, for it describes what should be the temper of heat in the body to dispose it for longevity. And this is useful, whether the spirits are detained or not; for in any case the heat of the spirits should be such as rather to act upon the hard parts than prey upon the soft; for the former intenerates and the latter dries up. Be: sides, the same thing is good to perfect alimentation ; for such a heat best excites the faculty of assimilation, and at the same time best prepares the matter to be assimilated. The properties of this kind of heat should be these: First, it should be slow, not sudden ; secondly, it should not be very intense, but moderate ; thirdly, it should be regular and not variable, that is, not alternately increasing and decreasing ; fourthly, if it meets with any resistance it should not be easily stifled or depressed. This operation is very subtle, but as it is one of the most useful it should not be neglected; and in the remedies proposed to invest the spirit with a robust heat, or that which I call operative, not predatory, I have in some measure answered this purpose.
RULE XI. The condensation of the spirits in their substance tends to longevity.
This rule is subordinate to the preceding; for the spirit when condensed receives all the four properties of heat there mentioned. But the methods of condensation are to be found in the first of the ten operations.
RULE XII. The spirit is more eager to escape and more predatory in large quantities than in small.
EXPLANATION. This rule is self-evident, seeing quantity of itself regularly increases power; as may be seen in flames, that the bigger the flame the stronger it breaks out and the quicker it consumes. And therefore too great an abundance or exuberance of the spirits is very injurious to longevity; and such a supply only is needed as will suffice for the offices of life and the furnishing of proper reparation.
RULE XIII. The spirit if equally diffused is less eager to go forth, and less predatory, than if it is distributed irregularly.
Not only is a large quantity of spirits in proportion to the whole injurious to the duration of things, but also the same quantity if less distributed is in like manner injurious. Therefore the more the spirit is broken up and dispersed the less predatory it is ; for dissolution begins wherever the spirit is most loose. And hence it is that exercise and frictions contribute much to longevity; for agitation is the best means of breaking up and intermingling things together in their smallest particles.
RULE XIV. An irregular and subsultory motion of the spirits does more to hasten their emission and is more predatory than a constant and equal one.
In inanimate bodies this rule is certain, for inequality is the mother of dissolution ; but in animate bodies (where repair as well as consumption is regarded, and repair proceeds by the appetite of things, which again is sharpened by variety) it holds less strictly; yet here also it may be received with this qualification, that the variety be rather an alternation than a confusion, and as it were constant in inconstancy.
The spirit in a body of firm texture is detained, though against its will.
All things abhor a solution of their continuity, but in a degree proportioned to their density and rarity. For the more rarefied bodies are, the smaller and narrower are the passages into which they suffer themselves to be compressed ; and therefore water will find
where dust will not, air where water will not, and flame and spirit where air will not. there is a limit to this; for the spirit is not so possessed with a desire of emission as to suffer itself to