It is a subject of enquiry among medical men, which kind of water is the most beneficial. They condemn, and with justice, all stagnant, sluggish, waters, and are of opinion that running water is the best, being rendered lighter and more salubrious by its current and its continuous agitation. Hence it is that I am much surprised that persons should be found to set so high a value as they do, upon cistern water. These last give as their reason, however, that rain-water must be the lightest water of all, seeing that it has been able to rise[1] aloft and remain suspended in the air. Hence it is, too, that they prefer snow-water to rain-water, and ice, again, to snow, as being water subtilized to the highest possible degree; on the ground that snow-water and ice-water must be lighter thin ordinary water, and ice, of necessity, considerably lighter. It is for the general interest, however, of mankind, that these notions should be refuted. For, in the first place, this comparative lightness which they speak of, could hardly be ascertained in any other way than by the sensation, there being pretty nearly no difference at all in weight between the kinds of water. Nor yet, in the case of rain-water, is it any proof of its lightness that it has made its way upwards into the air, seeing that stones,[2] it is quite evident, do the same: and then. besides, this water, while falling, must of necessity become tainted with the vapours which rise from the earth; a circumstance owing to which it is, that such numerous impurities[3] are to be detected in rain-water, and that it ferments[4] with such extreme rapidity.

I am, surprised, too, that snow[5] and ice should be regarded as the most subtilized states of this element, in juxtaposition with the proofs supplied us by hail, the water of which, it is generally agreed, is the most pernicious of all to drink. And then, besides, there are not a few among the medical men themselves, who assert that the use of ice-water and snow-water is highly injurious, from the circumstance that all the more refined parts thereof have been expelled by congelation. At all events, it is a well-ascertained fact that the volume of every liquid is diminished by congelation; as also that exces- sive dews[6] a reproductive of blight in corn, and that hoar- trosts result in blast; of a kindred nature, both of them, to snow. It is generally agreed, too, that rain-water putrefies with the greatest rapidity, and that it keeps but very badly on a voyage. Epigenes, however, assures us that water which has putrefied seven times and as often purified[7] itself, will no longer be liable to putrefaction. As to cistern-water, medical men assure us that, owing to its harshness, it is bad for the bowels and throat:[8] and it is generally admitted by them that ,there is no kind of water that contains more slime or more numerous insects of a disgusting nature. But it does not, therefore, follow that river water is the best of all, or that, in fact, of any running stream, the water of many lakes being found to be wholesome in the very highest degree.

What water, then, out of all these various kinds, are we to look upon as best adapted for the human constitution? Different kinds in different localities, is my answer. The kings of Parthia drink no water but that of the Choaspes[9] or of the Eulæus, and, however long their journies, they always have this water carried in their suite. And yet it is very evident that it is not merely because this water is river-water that it is thus pleasing to them, seeing that they decline to drink the water of the Tigris, Euphrates, and so many other streams.