Hume had despatched his five quartos, containing the whole history of England from the Roman period to the Revolution, in nine years.

Considering that the subject was new to him when he began, such rapidity made genuine research out of the question.

Robertson had the oddest way of consulting his friends as to what subject it would be advisable for him to treat, and was open to proposals from any quarter with exemplary impartiality; this only showed how little the stern conditions of real historic inquiry were appreciated by him.

In fact it is not doing them injustice to say that these eminent men were a sort of modern Livies, chiefly occupied with the rhetorical part of their work, and not over inclined to waste their time in ungrateful digging in the deep mines of historic lore.
Obviously the place was open for a writer who should unite all the broad spirit of comprehensive survey, with the thorough and minute patience of a Benedictine; whose subject, mellowed by long brooding, should have sought him rather than he it; whose whole previous course of study had been an unconscious preparation for one great effort which was to fill his life.

When Gibbon sat down to write his book, the man had been found who united these difficult conditions.
The decline and fall of Rome is the greatest event in history.