Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     Likewise,
'Tis nothing strange that all the breathing creatures
Seek, even by nature of their frame, their food.
Yes, since I've taught thee that from off the things
Stream and depart innumerable bodies
In modes innumerable too; but most
Must be the bodies streaming from the living-
Which bodies, vexed by motion evermore,
Are through the mouth exhaled innumerable,
When weary creatures pant, or through the sweat
Squeezed forth innumerable from deep within.
Thus body rarefies, so undermined
In all its nature, and pain attends its state.
And so the food is taken to underprop
The tottering joints, and by its interfusion
To re-create their powers, and there stop up
The longing, open-mouthed through limbs and veins,
For eating. And the moist no less departs
Into all regions that demand the moist;
And many heaped-up particles of hot,
Which cause such burnings in these bellies of ours,
The liquid on arriving dissipates
And quenches like a fire, that parching heat
No longer now can scorch the frame. And so,
Thou seest how panting thirst is washed away
From off our body, how the hunger-pang
It, too, appeased.