 Mill calls this insight “one of great weight and significance, which impresses a character on the whole mode of philosophical thinking of whoever receives it” (Examination, IX: 11). The doctrine ultimately pushes Mill towards Idealism. One might hold that, though we are only familiar in experience with mental impressions, we can nevertheless infer the existence of non-mental objects lying behind such mental objects. But such an inference could not be supported within experience by enumerative induction—no non-mental objects are ever observed behind mental objects—but only by a hypothesis to some unobserved entity. As was noted above, however, Mill rejects the method of hypothesis as an autonomous form of reasoning—no such inference to unobserved non-mental objects could for him be valid. Mill is forced towards the conclusion that we can have no warrant for believing in non-mental entities.