It is a question worth the asking, at what season in his life a man comes to the writing of history, with what equipment for the task, and under what impulsion. Cornelius Tacitus did not discover his vocation until he had passed the age of forty. Was that late or early? Late, in the opinion of some scholars, late and almost anomalous. Gaston Boissier avowed his surprise on the first page of his Tacite, a book published just over fifty years ago, and held in merited esteem for its combination of elegance and judgement. And, more recently (in 1947), Ernst Kornemann, the last survivor of that notable company, the pupils of Theodor Mommsen, affirmed it as an axiom that Tacitus came late to history.