The contents of his brain were as well kept as a careful trader's ledger.

He had his thoughts docketed and indexed, and rarely wasted the smallest portion of his time in searching for an idea.

Tonight he sat thinking until he was interrupted by a loud double knock, which was evidently familiar to him, for he muttered "George!" pushed aside his desk, and took up his stand upon the hearthrug, ready to receive the expected visitor.
There was the sound of a man's voice below,--very like Philip Sheldon's own voice; then a quick firm tread on the stairs; and then the door was opened, and a man, who himself was very like Philip Sheldon, came into the room.

This was the dentist's brother George, two years his junior.
The likeness between the two men was in no way marvellous, but it was nevertheless very obvious.

You could scarcely have mistaken one man for the other, but you could hardly have failed to perceive that the two men were brothers.