Page "Jean Grey" Paragraph 15

When her powers first manifest, Jean is unable to cope with her telepathy, forcing Professor X to suppress her access to it altogether.

Instead, he chooses to train her in the use of her telekinesis while allowing her telepathy to grow at its natural rate before reintroducing it.

When the Professor hides to prepare for the Z ' Nox, he reopens Jean's telepathic abiliites, which was initially explained by writers as Xavier ' sharing ' some of his telepathy with her.