Even if an opinion be indubitably true and undoubtingly believed, it will be a dead dogma, and not a living truth, if it be not fully, frequently, and fearlessly discussed. If the cultivation of the understanding consists of one thing more than another, it is surely in learning the grounds of one's own opinions, and these can only be fully learned by facing the arguments that favour the opposite opinions. He who knows only his own side of the case knows little of that. Unless he knows the difficulties which his truth has to encounter and conquer, he knows little of the force of his truth. Not only are the grounds of an opinion unformed or forgotten in the absence of discussion, but too often the very meaning of the opinion. When the mind is not compelled to exercise its powers on the questions which its belief presents to it, there is a progressive tendency to forget all of the belief except the formularies, until it almost ceases to connect itself at all with the inner life of the human being. In such cases a creed merely stands sentinel at the entrance of the mind and heart to keep them empty, as is so often seen in the case of the Christian creed as at present professed. So far we have considered only two possibilities--that the received opinion may be false and some other opinion consequently true, or that, the received opinion being true, a conflict with the opposite error is essential to a clear apprehension and deep feeling of the truth. But there is a commoner case still, when conflicting doctrines share the truth, and when the heretical doctrine completes the orthodox. Every opinion which embodies somewhat of the portion of the truth which the common opinion omits, ought to be considered precious with whatever amount of error and confusion it may be conjoined. In politics, again, it is almost a commonplace that a party of order or stability, and a party of progress or reform, are both necessary factors in a healthy political life. Unless opinions favourable to democracy and to aristocracy, to property, and to equality, to co-operation and to competition, to sociality and to individuality, to liberty and to discipline, and all the other standing antagonisms of practical life are expressed with equal freedom, and enforced and defended with equal talent and energy, there is no chance of both elements obtaining their due. Truth is usually reached only by the rough process of a struggle between combatants fighting under hostile banners. It may be objected, "But _some_ received principles, especially on the highest and most vital subjects, are more than half-truths." This objection is not sound. Even the Christian morality is, in many important points, incomplete and one-sided, and unless ideas and feelings not sanctioned by it had constituted to the formation of European life and character, human affairs would have been in a worse condition than they now are. _II.--Individuality as One of the Elements of Well-Being_