SECT. XLIX.—ON AIRS.
The best kind of air is that which is perfectly pure, such as that which is not defiled with the exhalation from lakes or marshes, nor from any pit which emits pestilential vapours. That also which is impregnated with the exhalations from a canal conveying the impurities of a city is deleterious, and indeed every kind which is loaded with vapours is not good; as also that which is contained within any hollow place, shut up on all sides by high mountains, and not admitting of ventilation. Those, therefore, which are thus deleterious, prove hurtful to all ages and temperaments, whereas the best kinds agree with all. But their differences as to quality—I mean heat, coldness, dryness, and humidity—have not the same effect upon all. Those of a proper temperament are benefited by temperate air, whereas those labouring under an intemperament derive benefit from the opposite kind.
Commentary. The first part of this Section is taken from Oribasius. (Synops. i, 24.) The remaining part will be found in the ‘Med. Collect.’ (ix, 1), where the subject is treated of at great length. See, also, Aëtius (iii, 162.) All these authors, however, are much indebted to Galen. (De Sanitate tuendâ, i.) According to Galen, the moon produces changes in the atmosphere, whereby she occasions putrefaction of dead bodies, impairs the colour, and hurts the head of living persons. (De Diebus Criticis, iii.) On the supposed causes why the moon occasions putrefaction, see Plutarch (Synops. iii.)
Antyllus says that there are many differences of airs: some arising from the season of the year; some from the changes of the moon; and some from the hour of the day or night; some from thickness or tenuity, motion or rest, or from the admixture of terrene exhalations. The sun, he adds, warms the body; but the moon rather humectates, and, therefore, she moistens the brain, and occasions the putrefaction of the flesh; renders the bodies of those who sleep in the open air more humid and obtuse; and, for the same cause, she induces epilepsy and heaviness of the head. Cold air, he says, produces plumpness, good nutrition, and the formation of fat; it promotes the growth of the body, and hence, the inhabitants of northern climates are remarked to possess this character. It is unsuitable, however, to all acute disorders; and is also improper for certain chronic diseases, such as consumption, cachexy, paralysis, apoplexy, and rheumatism. Warm air consumes the body, attenuating and wasting the system, but it is preferable to cold air for imparting vigour and agility; it tries the powers, is useful in affections of the nerves and chest, but not in those of other parts. Thick air has no other good property, except that it prevents the powers from being dissipated. Thin air is most conducive to health. The air of high situations is said by him to be more salubrious to all persons, except those labouring under diaphoresis or syncope, and the aged. The atmosphere of places near the sea, he remarks, is milder than that of inland parts. Places in the neighbourhood of marshes are at all times unhealthy; but, in summer, their atmosphere is pestilent. Those by a river side are cold and changeable. See more fully Stobæus. (Sermo xcix.)
Hippocrates gives many interesting observations on the effect of climate, and the state of the atmosphere, in influencing the health; but they are delivered so much in detail, that my limits do not admit of my entering into an exposition of them. (De Aëre Aquis, Locis.) The account there given of the effects of stagnant water when used as drink is particularly deserving of attention. He says it produces diseases of the spleen, dropsies, and the like. See Coray’s edition of this treatise.
Haly Abbas gives a very elaborate disquisition on this subject. He describes minutely the characters of salubrious airs, and the changes produced upon them by the seasons of the year, the state of the winds, the nature of countries, and the stars, that is to say, the sun and dog-star. (Theor. v.) See also Rhases (Contin. xxxiii); Avicenna (i, 2, 2.)
SECT. L.—ON WATERS.
It is necessary also to be skilled in the good and bad properties of waters, for of all things water is of most use in every mode of regimen. It is necessary to know that the best water is wholly devoid of quality, as regards taste and smell, is most pleasant to drink and pure to the sight; and when it passes through the præcordia quickly one cannot find a better drink. But such as remains long there, and proves pungent to the stomach, which it swells up with wind and loads, is to be reckoned pernicious. Such waters are neither soon heated nor cooled, and those things which are boiled in them are slowly and improperly boiled. It is better therefore to prove such water by trial, which he who wishes may do by attending to the following characters: Those which run to the north, and from the sun, pass slowly through the stomach, and are indigestible; they are slowly heated and cooled. Those which are strained through any passage or soil to the east are soon cooled and soon heated, and are to be supposed to be very good. Those also are good which are colder in summer and warmer in winter. Some judge of waters by weight, counting that the best which is lightest. This, if joined to the circumstances already mentioned, may be deserving of consideration, but is not of itself a sufficient criterion of goodness. Rain water, as Hippocrates remarks, is the lightest, the sweetest, the most limpid, and the thinnest, because that which is lightest and thinnest is attracted by the sun, who draws such particles to him, not only from all other waters, but also from the sea, and from bodies. Hence also it is the most prone to putrefaction, as being composed of many different qualities. Let no one suppose that the water which is most prone to putrefaction is the worst, for susceptibility of change is rather a good than a bad property; so that if it has the other characteristics of the best water, and is prone to putrefaction, it is to be reckoned the finest possible. When beginning to turn it proves the cause of hoarseness, coughs, and roughness of speech, to those who drink it. Of rain waters that which falls in summer and during thunder is preferable to that which falls in stormy weather. That from ice and snow is the worst, for during congelation the finest particles of the water are squeezed out. But waters which contain impurities, have a fetid smell, or any bad quality, may be so improved by boiling as to be fit to be drunk; or, by mixing them with wine, adding the astringent to that which is sweeter, and the others to the more austere. Some kinds of water it may be expedient to strain, such as the marshy, saltish, and bituminous. Those which are very cold are to be drunk after food, and not in great quantity. Some also have discovered certain articles of food and drink for correcting the bad properties of waters. Thus some beforehand drink of the decoction of chick-peas, or eat them; others, wild carrots boiled with some small fish, and fennel in like manner; whilst others again eat beet and gourds beforehand with salts and diluted wine.
Commentary. Our author has given an outline of Hippocrates’ opinions on this subject, and for fuller information, we must refer to his work quoted in [the preceding Section].