True-adi sankara appeared to establish the impersonal philosophy that god has no form and that wen we die, our soul will merge into this impersonal god. actually adi sankara is lord shiva himself and although this impersonal philosophy is not accepted by lord shiva himself, he appeared to teach this philosophy under the order of krishna as he was disturbed by the materialistic desires that people wanted krishna to grant. once adi sankara was about to be sacrificed by a kapalika (devotees of the goddess kali) but then he was saved by nrsimhadeva. then adi sankara composed the wonderful lakshmi nrsimha stotra which glorifies the lord.