De doctrina christiana (English: On Christian Doctrine or On Christian Teaching) is a theological text written by St. Augustine of Hippo. It consists of four books that describe how to interpret and teach the Scriptures. The first three of these books were published in 397 and the fourth added in 426. By writing this text, St. Augustine set three tasks for Christian teachers and preachers: to discover the truth in the contents of the Scriptures, to teach the truth from the Scriptures, and to defend scriptural truth when it was attacked. Starting in 389 A.D., the powerful application of faith to politics led Emperor Theodosius to issue a series of edicts against paganism that concluded in 391 with a law making pagan worship illegal. During the Golden Age of Athens, politics and manmade laws guided human conduct, and the city state was viewed as a manifestation of the highest human values, giving rise to political philosophy. Christianity effected a change in the course of Western society, requiring a new cultural identity and a new educational curriculum. With this aim in mind, Emperor Justinian (483-565 A.D.) cut off all state funding to chairs of rhetoric, essentially bringing the explicitly pagan classical tradition to a close. The pagan classical heritage would from this time onward be viewed through the lens of Christianity, increasing the need for an approach to the teaching of scripture that matched the sophistication of the classical inheritance. De doctrina christiana would provide the medieval world with that tool.