"It is plain, at least highly probable, that a life as long as that of the most aged of the patriarchs would be too short to answer your purposes; since the researches and disputes in which you are engaged have been already for a much longer time the objects of learned inquiries, and remain still as imperfect and undetermined as they were at first. But let me ask you again, and deceive neither yourself nor me, have you, in the course of these forty years, once examined the first principles and the fundamental facts on which all those questions depend, with an absolute indifference of judgment, and with a scrupulous exactness? with the same care that you have employed in examining the various consequences drawn from them, and the heterodox opinions about them? Have you not taken them for granted in the whole course of your studies? Or, if you have looked now and then on the state of the proofs brought to maintain them, have you not done it as a mathematician looks over a demonstration formerly made--to refresh his memory, not to satisfy any doubt? If you have thus examined, it may appear marvelous to some that you have spent so much time in many parts of those studies which have reduced you to this hectic condition of so much heat and weakness. But if you have not thus examined, it must be evident to all, nay, to yourself on the least cool reflection, that you are still, notwithstanding all your learning, in a state of ignorance. For knowledge can alone produce knowledge; and without such an examination of axioms and facts, you can have none about inferences." In this manner one might expostulate very reasonably with many a great scholar, many a profound philosopher, many a dogmatical casuist. And it serves to set the complaints about want of time, and the shortness of human life, in a very ridiculous but a true light. II RULES FOR THE STUDY OF HISTORY[7]