Kierkegaard wasn't really a philosopher in the academic sense. Yet he produced what many people expect of philosophy. He didn't write about the world, he wrote about life, about how we live and how we choose to live. His subject was the individual and his or her existence, the "existing being." In Kierkegaard's view, this purely subjective entity lay beyond the reach of reason, logic, philosophical systems, theology, or even "the pretenses of psychology." Nonetheless, it was the source of all these subjects. The branch of philosophy to which Kierkegaard gave birth has come to be known as existentialism.