Sutta Pitaka
Though both terms appear in the Sutta Pitaka, Gombrich and Brooks argue that the distinction as two "separate" paths originates in the earliest "interpretations" of the Sutta Pitaka, not in the suttas themselves. The suttas contain traces of ancient debates between Mahayana and Theravada schools in the interpretation of the teachings and the development of insight. Out of these debates developed the idea that bare insight suffices to reach liberation, by discerning the Three marks (qualities) of (human) existence (tilakkhana), namely dukkha (suffering), anatta (non-self) and anicca (impermanence).