 But as Hume discerns, the explanatory model of (i) lacks resources to secure anything like “same visible effect/same hidden cause”. That’s because Hume thinks there is always a barrier in moving from sensible qualities to the structure of hidden qualities. (In the literature on Newton, who also rejects (i), this is called the “transduction problem” since an influential article by McGuire 1970a.) Hume makes this point fully explicit in the first Enquiry: “he has not, by all his experience, acquired any idea or knowledge of the secret power, by which the one object produces the other” (EHU 5.4).