Complex sentence: Objectivism originated as the personal philosophy of Russian American writer Ayn Rand (1905--1982), expressed in her novels and polemic essays, and was later given more formal structure by Leonard Peikoff.
Split into simpler sentences: Objectivism originated as a new philosophy in the novels and polemic essays of Russian American writer Ayn Rand (1905--1982). It was later given more formal structure by Leonard Peikoff.