That is not the way to do justice to the arguments, or bring them into real contact with his own mind. He must be able to hear them from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form; he must feel the whole force of the difficulty which the true view of the subject has to encounter and dispose of; else he will never really possess himself of the portion of truth which meets and removes that difficulty. Ninety-nine in a hundred of what are called educated men are in this condition; even of those who can argue fluently for their opinions. Their conclusion may be true, but it might be false for anything they know: they have never thrown themselves into the mental position of those who think differently from them, and considered what such persons may have to say; and consequently they do not, in any proper sense of the word, know the doctrine which they themselves profess. They do not know those parts of it which explain and justify the remainder; the considerations which show that a fact which seemingly conflicts with another is reconcilable with it, or that, of two apparently strong reasons, one and not the other ought to be preferred. All that part of the truth which turns the scale, and decides the judgment of a completely informed mind, they are strangers to; nor is it ever really known, but to those who have attended equally and impartially to both sides, and endeavoured to see the reasons of both in the strongest light. So essential is this discipline to a real understanding of moral and human subjects, that if opponents of all important truths do not exist, it is indispensable to imagine them, and supply them with the strongest arguments which the most skilful devil's advocate can conjure up. 23 To abate the force of these considerations, an enemy of free discussion may be supposed to say, that there is no necessity for mankind in general to know and understand all that can be said against or for their opinions by philosophers and theologians. That it is not needful for common men to be able to expose all the misstatements or fallacies of an ingenious opponent. That it is enough if there is always somebody capable of answering them, so that nothing likely to mislead uninstructed persons remains unrefuted. That simple minds, having been taught the obvious grounds of the truths inculcated on them, may trust to authority for the rest, and being aware that they have neither knowledge nor talent to resolve every difficulty which can be raised, may repose in the assurance that all those which have been raised have been or can be answered, by those who are specially trained to the task.