Chapter 9.—How, and with Whom, Difficult Passages are to Be Discussed. 23.  For there are some passages which are not understood in their proper force, or are understood with great difficulty, at whatever length, however clearly, or with whatever eloquence the speaker may expound them; and these should never be brought before the people at all, or only on rare occasions when there is some urgent reason.  In books, however, which are written in such a style that, if understood, they, so to speak, draw their own readers, and if not understood, give no trouble to those who do not care to read them and in private conversations, we must not shrink from the duty of bringing the truth which we ourselves have reached within the comprehension of others, however difficult it may be to understand it, and whatever labor in the way of argument it may cost us.  Only two conditions are to be insisted upon, that our hearer or companion should have an earnest desire to learn the truth, and should have capacity of mind to receive it in whatever form it may be communicated, the teacher not being so anxious about the eloquence as about the clearness of his teaching.