On the doctrine that Dreams are sent from God, Books 1-2 (1.16-1.20)

Accordingly, we find that the four elements in the world are the earth, and the water, and the air, and the heaven, of which, even if some are difficult to find, they are still not classed in the utterly undiscoverable portion.

For that the earth, because it is a heavy, and indissoluble, and solid substance, is divided into mountains and champaign districts, and intersected by rivers and seas, so that some portion of it consists of islands, and some portions are continent. And again, some of it has a shallow and some a deep soil; and some is rough, and rugged, and strong, and altogether barren; and some is smooth and delicate, and exceedingly fertile; and besides all these facts we know a great number of others relative to the earth.

And again, there is the water, which we know has many of the aforesaid qualities in common with the earth, and many also peculiar to itself; for some of it is sweet, and some brackish, and some is mixed up of various characteristics; and some is good to drink, and some is not drinkable; and, moreover, neither of these last qualities is invariable with respect to every creature, but there are some to which it is

for there is in all sorts of places an infinite number of springs pouring forth hot water, not on the land only but even in the sea: at all events, there have appeared before now veins pouring up warm water in the middle of the sea, which all the enormous efflux of salt water in all the sea that encircles the world, pouring over them from all eternity, has never been able to extinguish, nor even in the least degree to diminish.

Again, we know that the air has an attractive nature, yielding to such bodies as surround it in an altitude of resistance, being the organ of life, and breath, and sight, and hearing, and all the rest of the external senses, admitting of rarification, and condensation, and motion, and tranquillity, and changes, and variations of every kind, by which it is altered and modified, and generating summers and winters, and the seasons of autumn and spring, by means of which the circle of the year is at last brought to a conclusion.