It has been maintained that there are illusions so beneficial as to be preferable to truth. Occasionally, in private life, we practise little deceptions upon individuals when the truth would cause some great temporary mischief. This case need not be discussed. The important instance is in reference to religious belief. A benevolent Deity and a future life are so cheering and consoling, it is said, that they should be secured against challenge or criticism; they ought not to be weakened by discussion. This, of course, assumes that these doctrines are unable to maintain themselves against opponents, that, with all their intrinsic charm (which nobody can be indifferent to), they would give way under a free handling. Such a confession is fatal. Men will go on cherishing pleasing illusions, but not such as need to be _protected_ in order to exist. According to Plato, the belief in the goodness of the Deity was of so great importance that it was to be maintained by state penalties--about the worst way of making the belief efficacious for its end. What should we think of an Act passed to imprison whoever disputed the goodness of King Alfred, the Man of Ross, or Howard? Granting that certain illusions are highly beneficial, it does not follow that they are to be exempted from criticism. Their effect depends on the prestige of their truth. That is, they must have reasons on their side. But a doctrine is not supported by reasons, unless the objections are stated and answered; not sham objections, but the real difficulties of an enquiring mind. If the statement of such difficulties is forcibly suppressed, the rational foundations will sooner or later be sapped. [FREEDOM ESSENTIAL TO THE SEARCH FOR TRUTH.] If illusions are themselves good, freedom of thought will give us the best. Why should we protect inferior illusions against the discovery of the superior? The unfettered march of the intellect may improve the quality of our illusions as illusions, while also strengthening their foundations. If religion be a good thing, the best religion is the best thing; and we cannot be sure of having the best, if men are forbidden to make a search. Supposing, then, truth is desirable, the means to the end are desirable. Now one of the means is perfect liberty to call in question every opinion whatsoever. This is not all that is necessary; it is not even the principal condition of the discovery of new truth. It is, however, an indispensable adjunct, a negative condition. While laborious search for facts, care in comparing them, genius in detecting deep identities, are the highways to knowledge,--the permission to promulgate new doctrines and to counter-argue the old is equally essential. Men cannot be expected to go through the toil of making discoveries at the hazard of persecution. If a few have done so, it is their glory and everybody else's shame.