But to resume. Even those proverbs which have acquired an use which seems to unite at once the trivial and the profane, may yet on closer inspection be found to be very far from having either triviality or profaneness cleaving to them. There is one, for instance, often taken lightly enough upon the lips: _Talk of the devil, and he is sure to appear_; or as it used to be: _Talk of the devil, and his imps will appear_; or as in German it is: _Paint the devil on the wall, and he will shew himself anon_;—which yet contains truth serious and important enough, if we would only give heed to it: it contains, in fact, a very solemn warning against a very dangerous sin, I mean, curiosity about evil. It has been often noticed, and is a very curious psychological fact, that there is a tendency in a great crime to reproduce itself, to call forth, that is, other crimes of the same character: and there is a fearful response which the evil we may hear or read about, is in danger of finding in our own hearts. This danger, then, assuredly makes it true wisdom, and a piece of moral prudence on the part of all to whom this is permitted, to avoid knowing or learning about the evil; especially when neither duty nor necessity oblige them thereto. It is men’s wisdom to talk as little about the devil, either with themselves or with others, as they can; lest he appear to them. “I agree with you,” says Niebuhr very profoundly in one of his letters,[212] “that it is better not to read books in which you make the acquaintance of the devil.” And certainly there is a remarkable commentary on this proverb, so interpreted, in the earnest warning given to the children of Israel, that they should not so much as _inquire_ how the nations which were before them in Canaan, served their gods, with what cruelties, with what abominable impurities, lest through this inquiry they should be themselves entangled in the same. (Deut. xii. 29, 30.) They were not to talk about the devil, lest he should appear to them.