The human mind has much more power of distinguishing between right and wrong, and between true and false, than of estimating with accuracy the comparative gravity of opposite evils. It is nearly always right in judging between right and wrong. It is generally wrong in estimating degrees of guilt, and the root of its error lies in the extreme difficulty of putting ourselves into the place of those whose characters or circumstances are radically different from our own. This want of imagination acts widely on our judgment of what is good as well as of what is bad. Few men have enough imagination to realise types of excellence altogether differing from their own. It is this, much more than vanity, that leads them to esteem the types of excellence to which they themselves approximate as the best, and tastes and habits that are altogether incongruous with their own as futile and contemptible. It is, perhaps, most difficult of all to realise the difference of character and especially of moral sensibility produced by a profound difference of circumstances. This difficulty largely falsifies our judgments of the past, and it is the reason why a powerful imagination enabling us to realise very various characters and very remote circumstances is one of the first necessities of a great historian. Historians rarely make sufficient allowance for the degree in which the judgments and dispositions even of the best men are coloured by the moral tone of the time, society and profession in which they lived. Yet it is probable that on the whole we estimate more justly the characters of the past than of the present. No one would judge the actions of Charlemagne or of his contemporaries by the strict rules of nineteenth-century ethics. We feel that though they committed undoubted crimes, these crimes are at least indefinitely less heinous than they would have been under the wholly different circumstances and moral atmosphere of our own day. Yet we seldom apply this method of reasoning to the different strata of the same society. Men who have been themselves brought up amid all the comforts and all the moralising and restraining influences of a refined society, will often judge the crimes of the wretched pariahs of civilisation as if their acts were in no degree palliated by their position. They say to themselves 'How guilty should I have been if I had done this thing,' and their verdict is quite just according to this statement of the case. They realise the nature of the act. They utterly fail to realise the character and circumstances of the actor.