When doubtful as to the use of words, I should have been helped by a better knowledge of Latin and enabled very often to write with a surer touch. Though compelled to resort frequently to the dictionary, I early learned to pay little attention to the definition but to regard with care the illustrative meaning in the citations from standard authors. When I began writing I used the Imperial Dictionary, an improvement over Webster in this respect. Soon the Century Dictionary began to appear, and best of all the New English Dictionary on historical principles edited by Murray and Bradley and published by the Clarendon Press at Oxford. A study of the mass of quotations in these two dictionaries undoubtedly does much to atone for the lack of linguistic knowledge; and the tracing of the history of words, as it is done in the Oxford dictionary, makes any inquiry as to the meaning of a word fascinating work for the historian. Amongst the multiplicity of aids for the student and the writer no single one is so serviceable as this product of labor and self-sacrifice, fostered by the Clarendon Press, to whom, all writers in the English language owe a debt of gratitude. Macaulay had a large fund of knowledge on which he might base his reasoning, and his indefatigable mind welcomed any outside assistance. He knew Greek and Latin thoroughly and a number of other languages, but it is related of him that he so thumbed his copy of Johnson's Dictionary that he was continually sending it to the binder. In return for his mastery of the languages, the dictionaries are fond of quoting Macaulay. If I may depend upon a rough mental computation, no prose writer of the nineteenth century is so frequently cited. "He never wrote an obscure sentence in his life," said John Morley;[11] and this is partly due to his exact use of words. There is never any doubt about his meaning. Macaulay began the use of Latin words at an early age. When four and a half years old he was asked if he had got over the toothache, to which question came this reply, "The agony is abated." Mathematics beyond arithmetic are of no use to the historian and may be entirely discarded. I do not ignore John Stuart Mill's able plea for them, some words of which are worth quoting. "Mathematical studies," he said, "are of immense benefit to the student's education by habituating him to precision. It is one of the peculiar excellences of mathematical discipline that the mathematician is never satisfied with an _a peu pres_. He requires the _exact_ truth.... The practice of mathematical reasoning gives wariness of the mind; it accustoms us to demand a sure footing."[12] Mill, however, is no guide except for exceptionally gifted youth. He began to learn Greek when he was three years old, and by the time he had reached the age of twelve had read a good part of Latin and Greek literature and knew elementary geometry and algebra thoroughly.