I am not thinking of those shining precepts which are the registered property of every school; that is to say — learn as much by writing as by reading; be not content with the best book; seek sidelights from the others; have no favourites; keep men and things apart; guard against the prestige of great names; see that your judgments are your own; and do not shrink from disagreement; no trusting without testing; be more severe to ideas than to actions; do not overlook the strength of the bad cause of the weakness of the good; never be surprised by the crumbling of an idol or the disclosure of a skeleton; judge talent at its best and character at its worst; suspect power more than vice, and study problems in preference to periods.

Many of these precepts which he quotes here have been quoted as originating with Lord Acton. - The Study of History (1895)