From Socrates Scholasticus, Ecclesiastical History, Bk.3, Chs. 12 and 16:
Observing that those who suffered martyrdom under the reign of Diocletian were greatly honored by the Christians, and knowing that many among them were eagerly desirous of becoming martyrs, Julian determined to wreak his vengeance upon them in some other way. Abstaining therefore from the excessive cruelties which had been practiced under Diocletian; he did not however altogether abstain from persecution (for any measures adopted to disquiet and assault I regard as persecution). This then was the plan he pursued: he enacted a law by which Christians were excluded from the cultivation of literature; 'lest,' said he, 'when they have sharpened their tongue, they should be able the more readily to meet the arguments of the heathen.'