Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     By what devices this strange state and new
May be occasioned, and by what the soul
Can be confounded and the frame grow faint,
I will untangle: see to it, thou, that I
Pour forth my words not unto empty winds.
In first place, body on its outer parts-
Since these are touched by neighbouring aery gusts-
Must there be thumped and strook by blows of air
Repeatedly. And therefore almost all
Are covered either with hides, or else with shells,
Or with the horny callus, or with bark.
Yet this same air lashes their inner parts,
When creatures draw a breath or blow it out.
Wherefore, since body thus is flogged alike
Upon the inside and the out, and blows
Come in upon us through the little pores
Even inward to our body's primal parts
And primal elements, there comes to pass
By slow degrees, along our members then,
A kind of overthrow; for then confounded
Are those arrangements of the primal germs
Of body and of mind. It comes to pass
That next a part of soul's expelled abroad,
A part retreateth in recesses hid,
A part, too, scattered all about the frame,
Cannot become united nor engage
In interchange of motion. Nature now
So hedges off approaches and the paths;
And thus the sense, its motions all deranged,
Retires down deep within; and since there's naught,
As 'twere, to prop the frame, the body weakens,
And all the members languish, and the arms
And eyelids fall, and, as ye lie abed,
Even there the houghs will sag and loose their powers.
Again, sleep follows after food, because
The food produces same result as air,
Whilst being scattered round through all the veins;
And much the heaviest is that slumber which,
Full or fatigued, thou takest; since 'tis then
That the most bodies disarrange themselves,
Bruised by labours hard. And in same wise,
This three-fold change: a forcing of the soul
Down deeper, more a casting-forth of it,
A moving more divided in its parts
And scattered more.