RULE XXX.

The cure of diseases requires temporary medicines; but longevity is to be procured by diets.

EXPLANATION.

Things which come by accident cease as soon as the causes are removed; but the continuous course of nature, like a flowing river, requires likewise a continual rowing or sailing against the stream; therefore we must work regularly by means of diets. Diets are of two kinds; set diets, which are to be used at certain times, and the common diet for daily life. And of these the former kind, that is, courses of medicine to be used for a time, are the more potent; for things that have power enough to turn back the course of nature are mostly too strong, and produce alterations too sudden to be safely taken into common use. Now, in the remedies proposed in conformity with these intentions, you will find only three set diets; namely, an opiate diet, an emollient diet, and a diet emaciating and renewing. But amongst the things which I have prescribed for common diet and daily life the most efficacious are these, which likewise have nearly the same force as set diets, namely, nitre and its subordinates; government of the affections, choice of pursuits; refrigerations which do not pass by the stomach; drinks that engender roscid juices; impregnation of the blood with some firmer substance, as pearls and woods; proper anointings to keep out the air and detain the spirit; applications of heat from without during the time of assimilation after sleep; caution with respect to such things as inflame the spirit and give it a predatory heat, as wines and spices; and a moderate and seasonable use of things which give a robust heat to the spirits, as saffron, cress, garlic, elecampane, and compound opiates.

RULE XXXI.

The living spirit perishes immediately, when it is deprived either of motion, or of refrigeration, or of aliment.

EXPLANATION.

These are the three things which before I called the porches of death, and they are the proper and immediate passions of

the spirit. For all the organs of the principal parts serve to perform these three offices; and again all destruction of the organs which causes death brings it to this, that one or more of these fail. Therefore all the rest are but different ways to death that end in these three. But the fabric of the parts is the organ of the spirit, as the spirit is the organ of the reasonable soul, which is incorporeal and divine.

RULE XXXII.

Flame is a momentary, air a permanent substance; the living spirits of animals are of a middle nature between the two.

EXPLANATION.

This matter requires a deeper investigation and a longer explanation than pertains to the present inquiry. In the meantime it should be known that flame is being continually generated and extinguished, so that it is only continued by succession. But air is a permanent body that is not dissolved; for though new air be created out of watery moisture, yet the old air still remains; whence comes that surcharge of the air mentioned in the title concerning the Winds. But the spirit partakes of both natures, both of flame and air; as likewise its nourishers are oil, which is homogeneous to flame, and air, which is homogeneous to water. For the spirit is not nourished by the oily part alone, nor by the watery part alone, but by both together; and though air does not sort well with flame nor oil with water, yet in a mixed body they agree well enough. Likewise the spirit gets from air its easy and delicate impressions and receptions, but from flame its noble and powerful motions and activity. In like manner also the duration of the spirit is a compound thing, not so momentary as flame, nor yet so permanent as air. And it differs the more from the conditions of flame because flame itself is extinguished by accident, namely, by contraries and the hostile bodies that surround it, a condition and necessity where to the spirit is not subject; and the spirit is repaired from the fresh and lively blood of the small arteries which are inserted into the brain, but this repair takes place according to its own manner, whereof I am not now speaking.