Read it through once

"The object of that person in that house was robbery, not murder. It is true that the safe was not open, but there was an ordinary tin cash-box on the table, with three thousand dollars in it. It is easily supposable that the thief was concealed in the house; that he knew of this box, and of its owner's habit of counting its contents and arranging his accounts at night--if he had that habit, which I do not assert, of course;--that he tried to take the box while its owner slept, but made a noise and was seized, and had to use the knife to save himself from capture; and that he fled without his booty because he heard help coming.