It seemed to David that in some boy of his own age he ought to find such a friend.

He had seen many boys--but he had not yet found the friend.
David had begun to think, indeed, that of all these strange beings in this new life of his, boys were the strangest.
They stared and nudged each other unpleasantly when they came upon him playing.

They jeered when he tried to tell them what he had been playing.

They had never heard of the great Orchestra of Life, and they fell into most disconcerting fits of laughter, or else backed away as if afraid, when he told them that they themselves were instruments in it, and that if they did not keep themselves in tune, there was sure to be a discord somewhere.
Then there were their games and frolics.

Such as were played with balls, bats, and bags of beans, David thought he would like very much.
But the boys only scoffed when he asked them to teach him how to play.
They laughed when a dog chased a cat, and they thought it very, very funny when Tony, the old black man, tripped on the string they drew across his path.