Jean-Marie was plainly not himself.

He had fits of hectic activity, when he made unusual exertions to please, spoke more and faster, and redoubled in attention to his lessons.

But these were interrupted by spells of melancholia and brooding silence, when the boy was little better than unbearable.
'Silence,' the Doctor moralised--'you see, Anastasie, what comes of silence.

Had the boy properly unbosomed himself, the little disappointment about the treasure, the little annoyance about Casimir's incivility, would long ago have been forgotten.

As it is, they prey upon him like a disease.