Mentalics refers to the ability to read and shape the minds of others. Second Foundation (novel) introduced mentalics to Asimov's readers. All members of the Second Foundation were taught to use this ability to aid the Seldon Plan whenever necessary. Mentalics is not limited to those of the Second Foundation, however: Gaia's constituents are gifted with it. The Mule's power stemmed from his Gaian origins. R. Daneel Olivaw and robots like him were also able to read and leave impressions upon other minds. Robots with mentalics are featured as early as "Liar!".