Read it through once

But it was not this night in particular that, in the solitude of his cabin, Ahab thus pondered over his charts. Almost every night they were brought out; almost every night some pencil marks were effaced, and others were substituted. For with the charts of all four oceans before him, Ahab was threading a maze of currents and eddies, with a view to the more certain accomplishment of that monomaniac thought of his soul.