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Well, then, do I ask you to believe that evaporation from land and water is the sole cause of wind? Do I affirm that it produces a weight in the atmosphere, the breaking up of which causes a rush of air? that at that moment what was previously dense and stationary gets rarefied and strives, as its nature requires, to obtain a wider space? I do approve of this as sometimes the explanation. But there is a far truer and more potent one, to wit, that the atmosphere by its constitution possesses a native capacity of movement, this power not being derived from an external source, but being like others of its powers inherent. For can you suppose that we men have been endued with strength to move about, while the atmosphere has been left sluggish and immovable? Water, too, has its own motion, even though the winds are at rest; otherwise it could not produce animal life. We see also forms of vegetable life like moss produced by water, and certain kinds of herbage floating on its surface.