Of all human errors those most in vogue are the most dangerous, for they are just those from which the most superior minds have the greatest difficulty in preserving themselves. It is impossible to see, without horror, into what aberrations of reason and of moral sense men otherwise most enlightened and virtuous may be led away by the predominant ideas of their age. And the horror becomes still greater when a discovery is made of the iniquities, sufferings, and calamities, public and private, consequent upon the admission of such aberrations amongst the choice spirits of the period. In the matter of religious liberty, St. Louis is a striking example of the vagaries which may be fallen into, under the sway of public feeling, by the most equitable of minds and the most scrupulous of consciences. A solemn warning, in times of great intellectual and popular ferment, for those men whose hearts are set on independence in their thoughts as well as in their conduct, and whose only object is justice and truth.
As for the crusades, the situation of Louis was with respect to them quite different and his responsibility far more personal. The crusades had certainly, in their origin, been the spontaneous and universal impulse of Christian Europe towards an object lofty, disinterested, and worthy of the devotion of men; and St. Louis was, without any doubt, the most lofty, disinterested, and heroic representative of this grand Christian movement. But towards the middle of the thirteenth century the moral complexion of the crusades had already undergone great alteration; the salutary effect they were to have exercised for the advancement of European civilization still loomed obscurely in the distance; whilst their evil results were already clearly manifesting themselves, and they had no longer that beauty lent by spontaneous and general feeling which had been their strength and their apology. Weariness, doubt, and common sense had, so far as this matter was concerned, done their work amongst all classes of the feudal community. As Sire de Joinville, so also had many knights, honest burghers, and simple country-folks recognized the flaws in the enterprise, and felt no more belief in its success. It is the glory of St. Louis that he was, in the thirteenth century, the faithful and virtuous representative of the crusade such as it was when it sprang from the womb of united Christendom, and when Godfrey de Bouillon was its leader at the end of the eleventh. It was the misdemeanor of St. Louis, and a great error in his judgment, that he prolonged, by his blindly prejudiced obstinacy, a movement which was more and more inopportune and illegitimate, for it was becoming day by day more factitious and more inane.