Urine day at E.T.A. (p. 155)
Hal Incandenza for a long time identified himself as a lexical prodigy who—though Avril had taken pains to let all three of her children know that her nonjudgmental love and pride depended in no way on achievement or performance or potential talent—had made his mother proud, plus a really good tennis player. Hal Incandenza is now being encouraged to identify himself as a late-blooming prodigy and possible genius at tennis who is on the verge of making every authority-figure in his world and beyond very proud indeed.
Context
The theme's psychology in two sentences, from the quarterly urine-testing day: "lexical prodigy" is not something Hal is so much as something he "identified himself as" — an identity whose whole payoff, the em-dash aside admits while denying it, was making Avril proud. The scene then shows the identity being swapped out for a tennis one by the same machinery of authority-figure pride.