Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     Thus, then, the massy weight of earth stood firm
With now concreted body, when (as 'twere)
All of the slime of the world, heavy and gross,
Had run together and settled at the bottom,
Like lees or bilge. Then ocean, then the air,
Then ether herself, the fraught-with-fire, were all
Left with their liquid bodies pure and free,
And each more lighter than the next below;
And ether, most light and liquid of the three,
Floats on above the long aerial winds,
Nor with the brawling of the winds of air
Mingles its liquid body. It doth leave
All there- those under-realms below her heights-
There to be overset in whirlwinds wild,-
Doth leave all there to brawl in wayward gusts,
Whilst, gliding with a fixed impulse still,
Itself it bears its fires along. For, lo,
That ether can flow thus steadily on, on,
With one unaltered urge, the Pontus proves-
That sea which floweth forth with fixed tides,
Keeping one onward tenor as it glides.