In Heart of Darkness, what keeps Marlow from joining the tribesmen when he watches them dance?
While traveling down the river, Marlow observes various natives taking part in ritual dances. The sight causes him to question the accepted status of civilized humanity, and wonder what he has that the natives do not, or vice versa. He is tempted to leave his mission and go ashore, to join the natives in their dance and create a simpler life:
You wonder I didn't go ashore for a howl and a dance? Well, no—I didn’t. Fine sentiments, you say? Fine sentiments, be hanged! I had no time.
I had to watch the steering, and circumvent those snags, and get the tin-pot along by hook or by crook.
(Conrad, Heart of Darkness, eNotes eText)
His personal responsibility to his mission is what keeps him focused on his work. While others are working on the steamer as well, Marlow believes that it is his own personal influence that keeps everyone working efficiently, and that he must attend to every small issue personally. Because of his commitment to performing to the best of his ability, he ultimately has no time for frivolous activities.