289. Ydor: i.e. water; Hippocrates and Galen say that it is compounded of two simple qualities, coldness and wetness, and that it does not contribute anything to the growth or nourishment, of the body unless it be compounded with other things. It counteracts everything that has hotness and dryness, and everything that counteracts hotness and wetness in this way is unable to nourish the body, because, as water quenches fire or as light overcomes darkness, that is how water quenches the natural heat. Nothing is nourished except by something that is like itself, but water is simple and the body is compound, Hence, since water does not have similarity with the body, the body is not nourished by it, as Galen says. It is compound things that grow and develop, and the opposite is true of simple things, so that, since water is simple, it gives no nourishment. To confirm that water is a simple, it is pointed out by Ysaac that every compound has a taste and smell, and as it is clear that water has neither taste nor smell, it is a simple.