This volume is a Bible history, reaching, in its present imperfect form, from Adam to the death of Saul. It has come to us only in a Latin translation (made from Greek, and that again from a Hebrew original), and by an accident the name of the great Jewish philosopher of the first century, Philo, has been attached to it. Let me say at once that the attribution of it to him is wholly unfounded, and quite ridiculous: nevertheless I shall use his name in italics ('Philo') as a convenient short title.
Its importance lies in this, that it is a genuine and unadulterated Jewish book of the first century--a product of the same school as the Fourth Book of Esdras and the Apocalypse of Baruch, and written, like them, in the years which followed the destruction of Jerusalem in A.D. 70. It is thus contemporary with some of the New Testament writings, and throws light upon them as well as upon the religious thought of the Jews of its time.
--from the Introduction