'So if we should handle BOOKS and STUDIES,' he continues, having handled custom and habit a little and their powers, in that profoundly suggestive manner, 'so if we should handle books and studies, and what influence and operation _they_ have upon manners, are there not divers precepts of _great caution_ and _direction_?' A question to be asked. And he goes on to make some further enquiries and suggestions which have considerably more in them than meets the ear. They appear to involve the intimation that many of our books on moral philosophy, come to us from the youthful and poetic ages of the world, ages in which sentiment and spontaneous conviction supplied the place of learning; for the accumulations of ages of experiment and conclusion, tend to maturity and sobriety of judgment in the race, as do the corresponding accumulations in the individual experience and memory. 'And the reason why books' (which are adapted to the popular belief in these early and unlearned ages) 'are of so little effect towards _honesty of life_, is that they are not read and _revolved_--revolved--as they should be, by _men in mature years_.' But unlearned people are always beginners. And it is dangerous to put them upon the task, or to leave them to the task of remodelling their beliefs and adapting them to the advancing stages of human development. He, too, thinks it is easier to overthrow the old opinions, than it is to discriminate that which is to be conserved in them. The hints here are of the most profoundly cautious kind--as they have need to be--but they point to the danger which attends the advancement of learning when rashly and unwisely conducted, and the danger of introducing opinions which are in advance of the popular culture; dangers of which the history of former times furnished eminent examples and warnings then; warnings which have since been repeated in modern instances. He proposes that books shall be tried by their effects on manners. If they fail to produce HONESTY OF LIFE, and if certain particular forms of truth which were once effective to that end, in the course of a popular advancement, or change of any kind, have lost that virtue, let them be examined; let the translation of them be scientifically accomplished, so that the main truth be not lost in the process, so that men be not compelled by fearful experience to retrace their steps in search of it, even, perhaps, to the resuming of the old, dead form again, with all its cumbrous inefficacies; for the lack of a leadership which should have been able to discriminate for them, and forestall this empirical procedure.