An entire body of philosophy according to the principles of the famous Renate Des Cartes in three books, (I) the institution ... (II) the history of nature ... (III) a dissertation of the want of sense and knowledge in brute animals ... / written originally in Latin by the learned Anthony Le Grand ; now carefully translated from the last corrections, alterations, and large additions of the author, never yet published ... by Richard Blome.

CHAP. XXI. Of the Appetite of Hunger and Thirst.

I. Why Hun∣ger and Thirst are called Na∣tural Appe∣tites or Desires. SEeing that Hunger and Thirst are perceived after the same manner, as the other Senses, viz. by the Ministry of the Nerves, which like so ma∣ny fine Threads proceed from the Brain to the Sto∣mach and Gullet; it seems convenient that having spoken of the Senses, we should now proceed to explain what Hunger and Thirst is. Which 2 af∣fections, are commonly called Natural Appetites, because they suppose a Compound of Soul and Bo∣dy, and are generally accompanied with a desire to Eat and Drink.

II. Aristotle's Opinion concerning Hunger and Thirst. ARISTOTLE defines Hunger to be a de∣sire of that which is hot and dry; but does not take notice whence this Appetite doth arise, nor how it comes to be stirred up; nor do I believe that any of his Qualities will be able to explicate the nature thereof. For we find that Infants and other new born Animals desire Milk; but who will say that the Appetite to Milk is only the de∣sire of that which is dry? Or shall we say that Animals when they desire Herbs and Fruits, are carried out with an Appetite to that which is Hot and Dry, when a moisture can be separated from them, which far surpasseth their dry substance in quantity? Again, how can Hunger be said to be the Appetite of that which is hot and Dry, seeing that Herbs and Fruits, according to all that we can perceive by them, have more cold than heat in them?

III. What Hun∣ger is, and how it is caused. Hunger therefore is nothing else but a Sense ari∣sing in the Ventricle, from an Acid Juice twitch∣ing the Nerves thereof. For as the various mo∣tions of the Optick Nerve, makes the Soul to per∣ceive and discern all the varieties of Light and Co∣lours; so there is nothing that can produce the sense of Hunger, but the motion of some Nerves in∣serted into the bottom of the Stomach. For the better understanding how this is done, we are to take notice that when the Stomach is empty of Food, the Juice or Liquor which is wont to flow out of the Arteries into the Stomach, and there to mingle with the Food, finding no matter to work upon, twitcheth the Nerves of the Stomach, which motion being conveyed to the Brain, stirs up the Sense of Hunger.

IV. No Liquor is conveyed out of the Spleen into the Sto∣mach. Some Physicians are of opinion, that this Li∣quor is conveyed into the Stomach by Veins from the Spleen: But that they are mistaken herein, is evident by this Experiment, that when a Ligature is made on the Vas Breve, the Vessel that lies be∣tween the Spleen and the Stomach, that part of it which is betwixt the Ligature and the Stomach swells, whereas the other part grows flag and em∣pty; which is a plain evidence that some liquor is conveyed by the said Vessel from the Stomach to the Spleen, and not from the Spleen to the Sto∣mach. Moreover, the Valvulae that are in the Vas Breve venosum, do oppose the transmission of any liquor from the Spleen to the Stomach, because all of them lead towards the Spleen. Whence it is manifest that something is transmitted from the Stomach to the Spleen, but not the contrary way.

V. The Nature of the Li∣quor that flows out of the Arte∣ries. Now this Liquor which causeth the sense of Hunger is sowre and sharp, as being the off-spring of Choler and Melancholy, and which therefore lighting on the bottom of the Stomach, cannot but twitch and prick the membrans whereof it doth consist. Hence it is commonly observed, that Melancholy Persons are great Eaters, because this Juice is more sowre in them, than in others, by which means the Food is soon consumed there∣by, as Metals are in Aqua Fortis, and other acid Spirits, and the Guts egg'd on to a ready Evacuation.

VI. Why some Persons are very sel∣dom sensible of Hunger. And on the contrary it sometimes happens, that persons who have not eaten of a good while, yet have no sense of Hunger, nor any desire to Eat, as it is frequently so with Phlegmatick Persons. Because this Juice by some obstruction or other is hindred from entring into the Stomach, or be∣cause it is too thin and weak, so that the Stomach is not sensible of the weak impression it makes up∣on it; or because its force is blunted by some cold and clammy Humour, or because there is but lit∣tle of this sharp Humour conveyed to the Stomach. For it is always one or other of these causes that occasions the want of Appetite to Food, and more especially in Sick People.

VII. Of Persons that are troubled with a Dogs hunger, as 'tis called. And on the other hand there are some persons that are troubled with continual Hunger, and who like Dogs are ever Ravenous, and never satisfied; because so great quantity of this sharp Humour is conveyed to their Stomachs, that all their Food thereby is made sowre, so that their Stomach is continually twitched, and sollicited to desire more Food, the former being readily evacuated down∣wards, or else cast up by Vomit. And thus it comes to pass, that some of this Humour is some∣times transmitted to the Venae Lacteae, and conti∣nually bes••egeth the Stomach.

VIII. The Irregu∣lar Appe∣tite of Wo∣men with Child. But if this sharp Humour, lodging in the bot∣tom of the Stomach, be of such a Temperament, as to have a peculiar force to dissolve some Food sooner than other, then it will be apt to stir up the Appetite of one sort of Meat rather than another. Hence some Women eat Coals, Chalk, Quick-lime and the like. Now the cause of this variety of this sowre Humour may be, because in the first Months of Conception, the Mouth of the Womb

being stopt, that the Superfluous Blood cannot be evacuated as formerly, by this means the Humours of the Body are corrupted, and being conveyed to the Stomach, produce an irregular Appetite. And therefore some Physicians are of opinion, that when the Melancholy Humour is deprav'd in Wo∣men, they long for Quick-lime, Coals, &c. when sowre Phlegm abounds in them they desire sowre things; and when Gall predominates, Bacon, Suet and such like. And it is from the same Cause that young Girls that are troubled with the Green-Sickness, as we commonlv call it, do take a liking to strange and unnatural sorts of Food, such as Coals, Chalk, Leather, &c. because their Blood for want of due evacuations grows sharper than ordinary, and consequently the Humour, which is derived out of the Blood into the Stomach, partaking of the same Quality, more violently twitches the Nerves thereof, and that after a pecu∣liar manner, according to the various constitution of the Blood in every Individual.

IX. It is not Heat that digests the meat in our Stomach. This discovers to us the mistake of the Peripate∣ticks, who suppose the Stomach to be like a Kitchin, where the Food is concocted and digested by heat only: whereas we find that there is but a moderate heat in the Stomach, and yet that even Bones are consumed and digested in it, as in the Stomach of a Dog, which if they should be boild for some Months together in a Pot with a very strong Fire, would never undergo any such change, as we find they do in the Stomach. Besides, Historians, and particularly P. Bressano in his Relation of New France, tell us of most ravenous and devour∣ing Fishes, which do readily digest the hardest Bodies and turn them into Liquor, whose Stomachs notwithstanding are so cold, that one can scarce∣ly endure to touch them; which is an incontesta∣ble Argument, that the dissolution of Food in the Stomach is not to be attributed to heat, but to the foresaid acid Juice in the Stomach, which dis∣solves our Food, as some acid Spirits do Me∣tals.

X. What Thirst and what Drink is. Thirst is a Desire of Drink, caused by the dry∣ness of the Throat and Gullet, or the Heat of the Stomach, commonly called Heart-burning, or a Salt Savour sticking to the Tongue. By the name of Drink we understand every sort of liquor, that is not Salt, Fat or too bitter, for Salt, Fat and Bitter Liquours do rather inflame the Thirst than allay it.

XI. What is the Cause of Thirst. To be informed of the Cause of Thirst, and that Driness which is sometimes in the Mouth, Tongue and Palate, we are to consider that the moisture which continually ascends from the Sto∣mach to the Gullet, in the form of a thick and moist Vapor, for the moistning of those parts, when at any time it is over agitated or heated, it doth so dry the Swallow, and at the same time so affect the Nerves, as to excite in the Soul the Ap∣petite of Thirst. So that there is a greater diffe∣rence between the Vapor which provokes Thirst, and that Liquor which produceth Hunger, than there is between Sweat, and that which exhales from the whole Body by insensible Transpira∣tion.

XII. Thirst is not an appetite of some∣thing that is cold. ARISTOTLE was of opinion that Natu∣ral Thirst was the Appetite or desire of something that is moist and cold. But this doth not seem probable; for tho' Thirst seem to be a desire of something that is moist, in order to dissolve, di∣lute and macerate the Food we have taken, and turn it into Juice; yet there is no need it should be cold rather than Hot; forasmuch as any moi∣sture doth extinguish Fire be it hot or cold. But whether it be more conducing to health to use Cold or Hot Drink is not so easily determinable, be∣cause of the different Temperaments of Bodies. Only we find by Experience, that the drinking of some extream cold liquor is very hurtful to the Body, whereas it is seldom known that any hurt accrues to us, by the using of hot drink.

XIII. Of the Dif∣ferent Causes of Thirst. Thirst is caused several ways, as either present∣ly after we have eaten, because of the driness of our Food, which like a Spung, drinks up the moi∣sture of our Stomach; or when our Throat is heated by the effusion of Gall, eating of high sea∣soned Meats, &c. or from some Salt Humour con∣veyed to that part, whence not only the imagina∣tion of drinking is awakened, but also an inordi∣nate desire thereof, by which means some persons long for Vinegar, Urin, Stinking Water, &c.