It was a very nice day, hinted Mycroft's father, to begin a long book. The ample young man stretched out gratefully on one of the porch chairs, Pilgrim's Progress in hand.
A small sharp face poked out of the overlooking window. Soon a slight boy surreptitiously followed it.
"You should use the door," said Mycroft.
His brother's eyes widened. "How'd you know I was here?"
"You're as loud as an ox."
"I was not either!"
Mycroft turned to him. "I thought I'd explained the art of deduction. . ."
"You mean you can teach me?"
"Not really."
"Try," said Sherlock, and Mycroft began.