Robin by Frances Hodgson Burnett

It was not a long time before he had left the house, but it seemed long and as if he had thought a great many rather incoherent things before he had reached the street and presently parted from his gay acquaintance and was on his way to his mother's house where she was spending a week, having come down from Scotland as she did often.

He walked all the way home because he wanted movement. He also wanted time to think things over because the intensity of his own mood troubled him. It was new for him to think much about himself, but lately he had found himself sometimes wondering at, as well as shaken by, emotional mental phases through which he passed. A certain moving fancy always held its own in his thoughts -- as a sort of background to them. It was in his feeling that he was in those weeks a Donal Muir who was unknown and unseen by the passing world. No one but himself -- and Robin -- could know the meaning, the feeling, the nature of this Donal. It was as if he lived in a new Dimension of whose existence other people did not know. He could not have explained because it would not have been understood. He could vaguely imagine that effort at explanation would end -- even begin -- by being so clumsy that it would be met by puzzled or unbelieving smiles.