So many valuable and important histories, so many necessary books on every subject, have been written by the professed infidel, as well as by the practical forgetter of God, that you must prepare yourself for a constant state of intellectual watchfulness, as to all the various opinions suggested by the different authors you study. It is not their opinions you want, but their facts. Most standard histories, even Hume and Voltaire, tell truth as to all leading facts: after half-a-century or so of filtration, truth becomes purified from contemporary passions and prejudices, and can be easily got at without any importantly injurious mixture.
It was to mark my often-repeated wish that you should philosophize for yourself, that I have omitted the names of Guizot and Hallam in the list of authors recommended for your perusal. With the tastes which I suppose you to possess and to acquire, you will not be likely to leave them out of your own list. The histories of Arnold and Niebuhr also belong to a distinct class of writings. I should prefer your being intimately acquainted with the so-called poetical histories which have been so long received and loved, before you interest yourself in these modern discoveries.
The lectures of Dr. Arnold upon Modern History contain, however, such a treasure of brilliant philosophy, of deep thought and forcible writing, that the sooner you begin them, and the more intimately you study them, the better pleased I should be. With respect to his singular views on religion and politics, you must always keep carefully in mind that his peculiar mental organization incapacitated him from forming correct opinions on any subject connected with imagination or metaphysics. You will soon be able to trace the manner in which the absence of these two powers affected all his reasonings, and closed up his mind against the most important species of evidence. I carry on the supposition that you have formed, or will form, all your views on religion and politics from your own judgment, assisted by the experience of those whose mind you know to be qualified by their many-sidedness to judge clearly and impartially—upon universal, not partial data. Remember, at the same time, however, that you belong to a church which professedly protests against popes of every description, against the unscriptural practice of calling any man “Father upon earth.” May you attend diligently, and in a child-like spirit of submission, to the teaching of that Holy and Apostolic Church, and there will then be no danger of your being led astray either by the infidel Hume or the sainted Arnold.