 In book 25 of his treatise On Nature (LS 20B–C), Epicurus also asserts that how we develop depends on us, and then he tries to show that it is self-refuting to maintain that all things occur of necessity. Unfortunately, while this is an important text for understanding Epicurus, it is also extremely unclear. Epicurus has a contorted and jargon-ridden writing style, and the text as we have it is full of gaps, because it is preserved on charred scrolls from an Epicurean villa buried by the eruption of Mount Vesuvius in 79 CE. So the summary of his arguments below, like any summary of this text, is bound to be controversial, and it is considerably more clear than Epicurus’ own arguments.