In the most secret chamber of the spirit of him who believes himself convinced that death puts an end to his personal consciousness, his memory, for ever, and all unknown to him perhaps, there lurks a shadow, a vague shadow, a shadow of uncertainty, and while he says within himself, "Well, let us live this life that passes away, for there is no other!" the silence of this secret chamber speaks to him and murmurs, "Who knows!... " These voices are like the humming of a mosquito when the south-west wind roars through the trees in the wood; we cannot distinguish this faint humming, yet nevertheless, merged in the clamor of the storm, it reaches the ear.

The Tragic Sense of Life (1913) - VI : In the Depths of the Abyss