Quote Identification

Identify speaker, plot and significance.

But I didn't call to him, for he gave a sudden intimation that he was content to be alone he stretched out his arms toward the dark water in a curious way, and, far as I was from him, I could have sworn he was trembling. Involuntarily I glanced seaward and distinguished nothing except a single green light, minute and far away, that might have been the end of a dock.