It is by a pure mechanism that may be explained the phenomena of habit, as well physical as moral; the soul, notwithstanding its spirituality, is modified exactly in the same manner as the body. Habit, in man, causes the organs of voice to learn the mode of expressing quickly the ideas consigned to his brain, by means of certain motion, which, during his infancy, the tongue acquires the power of executing with facility: his tongue, once habituated to move itself in a certain manner, finds much trouble, has great pain, to move itself after another mode; the throat yields with difficulty to those inflections which are exacted by a language different from that to which he has, been accustomed. It is the same with regard to his ideas; his brain, his interior organ, his soul, inured to a given manner of modification, accustomed to attach certain ideas to certain objects, long used to form to itself a system connected with certain opinions, whether true or false, experiences a painful sensation, whenever he undertakes to give it a new impulse, or alter the direction of its habitual motion. It is nearly as difficult to make him change his opinions as his language. Here, then, without doubt, is the cause of that almost invincible attachment which man displays to those customs--those prejudices--those institutions of which it is in vain that reason, experience, good sense prove to him the inutility, or even the danger. Habit opposes itself to the clearest, the most evident demonstrations; these can avail nothing against those passions, those vices, which time has rooted in him--against the most ridiculous systems--against the most absurd notions--against the most extravagant hypotheses--against the strangest customs: above all, when he has learned to attach to them the ideas of utility, of common interest, of the welfare of society. Such is the source of that obstinacy, of that stubbornness, which man evinces for his religion, for ancient usages, for unreasonable customs, for laws so little accordant with justice, for abuses, which so frequently make him suffer, for prejudices of which he sometimes acknowledges the absurdity, yet is unwilling to divest himself of them. Here is the reason why nations contemplate the most useful novelties as mischievous innovations--why they believe they would be lost, if they were to remedy those evils to which they have become habituated; which they have learned to consider as necessary to their repose; which they have been taught to consider dangerous to be cured.