Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     Into being
The clouds condense, when in this upper space
Of the high heaven have gathered suddenly,
As round they flew, unnumbered particles-
World's rougher ones, which can, though interlinked
With scanty couplings, yet be fastened firm,
The one on other caught. These particles
First cause small clouds to form; and, thereupon,
These catch the one on other and swarm in a flock
And grow by their conjoining, and by winds
Are borne along, along, until collects
The tempest fury. Happens, too, the nearer
The mountain summits neighbour to the sky,
The more unceasingly their far crags smoke
With the thick darkness of swart cloud, because
When first the mists do form, ere ever the eyes
Can there behold them (tenuous as they be),
The carrier-winds will drive them up and on
Unto the topmost summits of the mountain;
And then at last it happens, when they be
In vaster throng upgathered, that they can
By this very condensation lie revealed,
And that at same time they are seen to surge
From very vertex of the mountain up
Into far ether. For very fact and feeling,
As we up-climb high mountains, proveth clear
That windy are those upward regions free.