It's--it's, as Sarah says--it's narrowing.

I can see the effects of it upon you all," said Peter, calmly, "when I come back here." He could not fathom the wistfulness which clouded the blue eyes she lifted to his face.
"It is very narrowing," she said humbly.
"One may devote one's self to one's duties as a landed proprietor," said Peter, with another recurrence of pomposity, "and yet see something of one's fellow-men." He replaced the eyeglass, and walked up and down the room for a few moments, as though he were pacing a quarter-deck.

He looked very tall, and very, very slight and thin; older than his years, tanned and dried by the African sun, which had enhanced his natural darkness.

Though he spoke as a boy, he looked like a man.

His mother's heart yearned over him.
Peter had taken his lack of perception with him into the heart of South Africa, and brought it back intact.