 These formulations immediately raise several questions. What does it mean for something to be conceived “through itself”, i.e., in some sense be self-explanatory? Does the equivalence of causes and reasons suggested by E1p11altd1 mean that only appeals to causes can furnish reasons? Indeed, what counts as a “reason” (cf. Lin 2018)? It’s often assumed that in Spinoza’s view to give a “reason” for something requires engaging in the sort of apriori deductions that fill large swathes of the Ethics. The opening definition of the treatise, according to which something is a “cause of itself” if its existence is implied by its essence (E1def1), suggests that at least some of the relevant “reasons” will indeed be accessible apriori. But could sense experience also furnish us with reasons? Is seeing my dog play with a stick enough of a “reason” to “conceive” of her as existing, or must I deduce her necessary existence from the infinitely long series of prior causes (E1p28), a task Spinoza admits is impossible for finite minds like ours (Treatise on the Emendation of the Intellect [= TIE] §100)?