In the next place, it must be observed that every moral disposition brings with it an intellectual bias which exercises a great and often a controlling and decisive influence even upon the most earnest enquirer. If we know the character or disposition of a man, we can usually predict with tolerable accuracy many of his opinions. We can tell to what side of politics, to what canons of taste, to what theory of morals he will naturally incline. Stern, heroic, and haughty natures tend to systems in which these qualities occupy the foremost position in the moral type, while gentle natures will as naturally lean towards systems in which the amiable virtues are supreme. Impelled by a species of moral gravitation, the enquirer will glide insensibly to the system which is congruous to his disposition, and intellectual difficulties will seldom arrest him. He can have observed human nature with but little fruit who has not remarked how constant is this connection, and how very rarely men change fundamentally the principles they had deliberately adopted on religious, moral, or even political questions, without the change being preceded, accompanied, or very speedily followed, by a serious modification of character. So, too, a vicious and depraved nature, or a nature which is hard, narrow, and unsympathetic, will tend, much less by calculation or indolence than by natural affinity, to low and degrading views of human nature. Those who have never felt the higher emotions will scarcely appreciate them. The materials with which the intellect builds are often derived from the heart, and a moral disease is therefore not unfrequently at the root of an erroneous judgment.