Joseph, whose life followed that of the patriarchs, is the type of the political life, the model of the man of action and ambition. Taken alone, this is inferior to the life of the saint and philosopher, but mixed with the other it produces the perfect man, for the truly good man must take his part in public life. The story of Joseph, then, illustrates the full humanity of Moses' scheme, and it marks also, according to Philo, the great moral lesson, that if there be one spark of nobility in a man's soul, God will find it and cause it to shine forth.[141] For Joseph, until he comes down to Egypt, is not a virtuous man, but full of conceit and unworthy aspiration for supremacy; he shows his true worth when he is sold into slavery; and then by the Divine inspiration he becomes the ideal statesman. Very suggestive is Philo's homily, by which he develops the Bible narrative, that the function of the statesman is to expound dreams;[142] because his task is to interpret the life of man, which is one long dream of changing scenes, wherein we forget what has gone before, as the fleeting shadow leads us from childhood to youth, from youth to manhood, from manhood to old age. Lastly, from the story of Joseph he draws the lesson that when the Hebrew has attained to a high position in a foreign land, as in Egypt, where there is utter blindness about the true God, he can and should retain his national laws,[143] and not assimilate the practices of his environment. Eusebius[144] mentions, among the works of Philo which he had before him, a book on "The Statesman," in which doubtless the principles of government and social life were more fully treated. The book has disappeared, but the life of Joseph suffices to show that Philo recognized the place of public service in the human ideal.