organised priesthoods for religious purposes, you would be inevitably including a vast number of other purposes in the self-same destination. This does not in the least prejudice practical ways of dealing with certain existing circumstances, such as the propriety or justice of allowing a catholic people to have a catholic university. It is only an argument against erecting into a complete and definite formula the division of a society into two great castes, the one with a religion of the spirit, the other with a creed of the letter. Again, supposing that the enlightened caste were to consent to abandon the common people to what are assumed to be lower and narrower forms of truth,--which is after all little more than a fine phrase for forms of falsehood,--what can be more futile than to suppose that such a compromise will be listened to for a single moment by a caste whose first principle is that they are the possessors and ministers, not of an inferior or superior form of truth, but of the very truth itself, absolute, final, complete, divinely sent, infallibly interpreted? The disciples of the relative may afford to compromise. The disciples of the absolute, never. We shall see other objections as we go on to this state of things, in which a minority holds true opinions and abandons the majority to false ones. At the bottom of the advocacy of a dual doctrine slumbers the idea that there is no harm in men being mistaken, or at least only so little harm as is more than compensated for by the marked tranquillity in which their mistake may wrap them. This is not an idea merely that intellectual error is a pathological necessity of the mind, no more to be escaped than the pathological necessities which afflict and finally dissolve the body. That is historically true. It is an idea that error somehow in certain stages, where there is enough of it, actually does good, like vaccination. Well, the thesis of the present chapter is that erroneous opinion or belief, in itself and as such, can never be useful. This may seem a truism which everybody is willing to accept without demur. But it is one of those truisms which persons habitually forget and repudiate in practice, just because they have never made it real to themselves by considering and answering the objections that may be brought against it. We see this repudiation before our eyes every day. Thus for instance, parents theoretically take it for granted that error cannot be useful, while they are teaching or allowing others to teach their children what they, the parents, believe to be untrue. Thus husbands who think the common theology baseless and unmeaning, are found to prefer that their wives shall not question this theology nor neglect its rites. These are only two out of a hundred examples of the daily admission that error may be very useful to other people. I need hardly say that to deny this, as the commonplace to which this chapter is