Immanuel Kant (1724-1804), a German philosopher and scientist, is considered a central figure in modern philosophy. The core of his philosophical writings argue that the universe in itself is not "knowable" and that human mind structure is influenced by experience. He proposed that reason is the source of morality, aesthetics are a function of a disinterested judgement, and space and time are a function of human sensibility. While Kant's actual religious leanings are still being debated, his view on politics was that perpetual peace was an achievable goal through universal democracy and international cooperation. His emphasis on the role of the human mind in the perception of reality essentially reversed many of the previously accepted Christianity-based philosophical ideas.