 It is evident that the foundations of this argument rest with the related causal principles that everything must have a cause or ground for its existence and that no effect can have any perfection that is not also in its cause. To deny either of these causal principles is, on Clarke’s account, to reject the more general principle that “nothing can come from nothing” (a principle that the atheists such as Lucretius have themselves acknowledged). In the Treatise Hume develops an account of causation that directly contradicts these causal principles. Contrary to the causal maxim, Hume maintains, it is entirely possible for us to conceive of something beginning to exist without any cause. To deny this implies no contradiction and, therefore, this principle is neither intuitively nor demonstratively certain (T, 1.3.3/78–9). Granting that whatever is conceivable or non-contradictory is possible, it follows that it is possible that there exists a causal series that came into existence uncreated or has always existed without any further cause or ground for its existence. 