time. (2) Since the mind tends to confuse closely resembling ideas, it will naturally confuse a case of interrupted observation of an invariable object with a case of perfect identity. (3) This combination of perfect identity and interrupted observation creates cognitive dissonance, which is resolved by fabricating continued existence. (4) This fiction is enlivened into a full-fledged belief by the memory's "lively impressions" of the observed object. But this naïve belief in the continued and distinct existence of our perceptions is false, as is easily shown by simple observations. Philosophers therefore distinguish mental perceptions from external objects. But, Hume argues, this philosophical "system of a double existence" could never arise directly from reason or the imagination. Instead, it is "the monstrous offspring of two principles", viz. our naïve belief in the continued and distinct existence of our perceptions, along with our more reflective conclusion that perceptions must depend upon the mind. It is only by passing through the naïve natural belief that the imagination fabricates this "arbitrarily invent[ed]" philosophical system. Hume ends by voicing strong doubts about any system based on "such trivial qualities of the fancy", and recommending "[c]arelessness and in-attention" as the only remedy for scepticism. Sections 3–6 Next, Hume presents a brief critique of "antient philosophy" (traditional Aristotelianism) and "modern philosophy" (post-Scientific Revolution mechanical philosophy), focusing on their rival conceptions of external objects. As for the incomprehensible "fictions of the antient philosophy", he thinks they can shed further light on human psychology. We begin with contradictions in "our ideas of bodies": between seeing bodies as ever-changing bundles of distinct qualities, and seeing bodies as simple unities that retain their identity across time. We reconcile these contradictions by fabricating "something unknown and invisible" that underlies change and unifies the distinct qualities together: i.e., the substance of traditional metaphysics. Similar fictions, fabricated by the imagination to resolve similar difficulties, include substantial forms, accidents, and occult qualities, all meaningless jargon used only to hide our ignorance. Modern philosophy, however, claims to disown the "trivial propensit[ies] of the imagination" and follow only solid reason (or, for Hume, "the solid, permanent, and consistent principles of the imagination"). Its "fundamental principle" is that secondary qualities ("colours, sounds, tastes, smells, heat and cold") are "nothing but impressions in the mind", as opposed to the primary qualities ("motion, extension, and solidity") that exist in reality. But Hume argues that primary qualities cannot be conceived apart