In the universe anything that happens comes from the essential nature of objects, or of God or Nature. According to Spinoza, reality is perfection. If circumstances are seen as unfortunate it is only because of our inadequate conception of reality. While components of the chain of cause and effect are not beyond the understanding of human reason, human grasp of the infinitely complex whole is limited because of the limits of science to empirically take account of the whole sequence. Spinoza also asserted that sense perception, though practical and useful, is inadequate for discovering truth. His concept of "conatus" states that human beings' natural inclination is to strive toward preserving an essential being, and asserts that virtue/human power is defined by success in this preservation of being by the guidance of reason as one's central ethical doctrine. According to Spinoza, the highest virtue is the intellectual love or knowledge of God/Nature/Universe.