I think it proper before I commence my proposed work to pass under review the condition of the capital, the temper of the armies, the attitude of the provinces, and the elements of weakness and strength which existed throughout the whole Empire, 50 that we may become conversant, not only with the vicissitudes and issues of events, which are often matters of chance, but also with their relations and causes. — tacitus, Tile History, bk. I, Ch. Iv.