In Heart of Darkness, what is Marlow's view of the meaning of life?
Marlow has been changed by his experiences in the jungle, even more so by his meeting with Kurtz. Where once he was idealistic, even naive, he is now entirely a cynic, believing that man is meant to travel through life alone, and so die alone; further, the inner soul of a man cannot be transmitted to others, as they cannot hope to understand the individual plight. This comes partly from the way he finds Kurtz in the jungle, a man of immense power with no one to stand for him except in fear, and partly from the intense isolation he himself feels in the jungle, as if it is a living thing holding him away from civilization.
"...No, it is impossible; it is impossible to convey the life-sensation of any given epoch of one's existence, --that which makes its truth, its meaning -- its subtle and penetrating essence. It is impossible. We live, as we dream -- alone...."
(Conrad, Heart of Darkness, gutenberg.org)
His feeling is echoed in the various events of the novel, from the native attack on the steamship -- which he sees at first as entirely random and meaningless, without a larger purpose or goal -- to Kurtz's own descent into madness. Had Kurtz been able to remain sane and become a force for progress instead of destruction, his effect on Marlow may have been more positive; as it stands, when he finally meets Kurtz, all of Marlow's pessimistic suspicions are validated.