"Any Judge," he says, "one might suppose, would find it easy to describe the process which he had followed a thousand times and more. Nothing could be farther from the truth." In telling of the study of precedents in arriving at the rule of law to be applied to the decision of cases, he takes up, first, in the introduction, the method of philosophy and inquiries, in what proportions different sources of information shall be allowed to contribute to the result. If a precedent is applicable, when shall he refuse to follow it, and if no precedent is applicable, how does he reach the rule that will make a precedent for the future? "If," he says, "I am seeking logical consistency, the symmetry of the legal structure, how far shall I seek it? At what point shall the quest be halted by some discrepant custom, by some consideration of the social welfare; by my own or the common standards of justice or morals?" And again, he says: "The first thing he does is to compare the case before him with the precedents, whether stored in his mind or hidden in the books. I do not mean that the precedents are ultimate sources of the law, supplying the sole equipment for the legal armory, the sole tools, to borrow Maitland's phrase, 'in the legal smithy.' Back of precedents are the basic juridical conceptions which are the postulates of judicial reasoning, and farther back are the habits of life, the institutions of society, in which those conceptions had their origin, and which, by a process of interaction, they have modified in turn."
In the lecture on the methods of History, Tradition and Sociology, he shows how the method of Philosophy comes in competition with other tendencies which find their outlets in other methods. The tendency of a principle to expand itself to the limit of its logic may be counteracted by the tendency to confine itself within the limits of its history. "Very often," he says, quoting Justice Holmes, "the effect of history is to make the path of logic clear. History, in illuminating the past, illuminates the present, illuminates the future."
The law of real property supplies the readiest example of a field where there can be no progress without history, and where "a page of history," to quote Holmes again, "is worth a volume of logic."