19/19 1865.] [Footnote 5: A few subtle philosophers have returned to it, as I shall show later in chapter iv.] [Footnote 6: Thus, the perplexity in which John Stuart Mill finds himself is very curious. Having admitted unreservedly that our knowledge is confined to sensations, he is powerless to set up a reality outside this, and acknowledges that the principle of causality cannot legitimately be used to prove that our sensations have a cause which is not a sensation, because this principle cannot be applied outside the world of phenomena.] [Footnote 7: See p. |