José Ortega y Gasset decide and create a "project of life"—thus not be like those who live a conventional life of customs and given structures who prefer an unconcerned and imperturbable life because they are afraid of the duty of choosing a project. With a philosophical system that centered around life, Ortega y Gasset also stepped out of Descartes' "cogito ergo sum" and asserted "I live therefore I think". This stood at the root of his Kantian-inspired perspectivism, which he developed by adding a non-relativistic character in which absolute truth does exist and would be obtained by the sum of all perspectives of all
Cogito, ergo sum ("If I am mistaken, I am") (book XI, 26), and also anticipates modern refutations of the concept. Furthermore, in the "Enchiridion" Augustine attempts to refute skepticism by stating, "[B]y not positively affirming that they are alive, the skeptics ward off the appearance of error in themselves, yet they do make errors simply by showing themselves alive; one cannot err who is not alive. That we live is therefore not only true, but it is altogether certain as well" (Chapter 7 section 20). In 1640 correspondence, Descartes thanked two colleagues for drawing his attention to Augustine and notes similarity and difference.