Macaulay now concentrated all his energies on the History, which occupied his thoughts, his studies, and his pen for the most part during the remainder of his life.  The first two volumes were published in the latter part of 1848; and the sale was immense, surpassing that of any historical work in the history of literature, and coming near to the sale of the novels of Sir Walter Scott.  The popularity of the work was not confined to scholars and statesmen and critics, but it was equally admired by ordinary readers; and not in England and Scotland alone, but in the United States, in France, in Holland, in Germany, and other countries.

The labor expended on these books was prodigious.  The author visited in person nearly all the localities in England and Ireland where the events he narrated took place.  He ransacked the archives of most of the governments of Europe, and all the libraries to which he could gain access, public and private.  He worked twelve hours a day, and yet produced on an average only two printed pages daily,—­so careful was he in verifying his facts and in arranging his materials, writing and rewriting until no further improvement could be made.

This book was not merely the result of his researches for the last fifteen years of his life, but of his general reading for nearly fifty years, when everything he read he remembered.  Says Thackeray, “He reads twenty books to write a sentence; he travels one hundred miles to make a line of description.”  The extent and exactness of his knowledge were not only marvellous, but almost incredible.  Mr. Buckle declared that Macaulay was perfectly accurate in all the facts which Buckle had himself investigated to write his “History of Civilization;” and so particular was he in the selection of words that he never allowed a sentence to pass muster until it was as good as he could make it.  “He thought little of reconstructing a paragraph,” says his biographer, “for the sake of one happy illustration.”  He submitted to the most tiresome mechanical drudgery in the correction of his proof-sheets.  The clearness of his thought amid the profusion of his knowledge was represented in his writing by a remarkable conciseness of expression.  His short, vigorous sentences are compact with details of fact, yet rich with color.  His terseness has been compared to that of Tacitus.  His power of condensation, aptness of phrase and epithet, and indomitable industry made him a master of rhetorical effect, in the use of his multifarious learning for the illustration of his themes.

As soon as his last proof-sheet had been despatched to the printers, Macaulay at once fell to reading a series of historians from Herodotus downward, to measure his writings with theirs.  Thucydides especially utterly destroyed all the conceit which naturally would arise from his unbounded popularity, as expressed in every social and literary circle, as well as in the Reviews.  Like Michael Angelo, this Englishman