One demanded a reason why the sailors take up the water for their occasions out of the river Nile by night, and not by day. Some thought they feared the sun, which heating the liquid would make it more liable to putrefaction. For everything that is warmed becomes more easy to be changed, having already suffered when its natural quality was remitted. And cold constipating the parts seems to preserve everything in its natural state, and water especially. For that the cold of water is naturally constringent is evident from snow, which keeps flesh from corrupting a long time. And heat, as it destroys the proper quality of other things, so of honey, for it being boiled is itself corrupted, though when raw it preserves other bodies from corruption. And that this is the cause, I have a very considerable evidence from standing pools; for in winter they are as wholesome as other water, but in summer they grow bad and noxious. Therefore the night seeming in some measure to resemble the winter, and the day the summer, they think the water that is taken up at night is less subject to be vitiated and changed. To these seemingly probable reasons another was added, which confirmed the ingenuity of the sailors by a very strong proof. For some said that they took up their water by night because then it was clear and undisturbed; but at day-time, when a great many fetched water together, and many boats were sailing and many beasts swimming upon the Nile, it grew thick and muddy, and in that condition it was more subject to corruption. For mixed bodies are more easily corrupted than simple and unmixed; for from mixture proceeds disagreement of the parts, from that disagreement a change, and corruption is nothing else but a certain change; and therefore painters call the mixing of their colors [Greek omitted], corrupting; and Homer expresseth dyeing by [Greek omitted] (TO STAIN OR CONTAMINATE). Commonly we call anything that is simple and unmixed incorruptible and immortal. Now earth being mixed with water soonest corrupts its proper qualities, and makes it unfit for drinking; and therefore standing water stinks soonest, being continually filled with particles of earth, whilst running waters preserve themselves by either leaving behind or throwing off the earth that falls into them. And Hesiod justly commends The water of a pure and constant spring.