How can he prove it?
Why, these poor blackguards lying about are very fair specimens of humanity .-- And how much have they been bothered since they were born with aspirations after anything infinite, except infinite sour wine?
To eat, to drink; to destroy a certain number of their species; to reproduce a certain number of the same, two-thirds of whom will die in infancy, a dead waste of pain to their mothers and of expense to their putative sires....

and then--what says Solomon?
What befalls them befalls beasts.

As one dies, so dies the other; so that they have all one breath, and a man has no pre-eminence over a beast; for all is vanity.

All go to one place; all are of the dust, and turn to dust again.

Who knows that the breath of man goes upward, and that the breath of the beast goes downward to the earth?
Who, indeed, my most wise ancestor?
Not I, certainly.