This is one of the key passages of the novel, lifted above the train of Charles Gould's reflections by the narrator's approval. Note that the passage endorses action while explicitly admitting the ultimate futility of it ("flattering illusions," "sense of"). Conrad is saying here that mankind has no such mastery over the Fates, but requires some illusion to keep that knowledge at bay.

See the echo of this comment at Decoud's death.