In his speech On Imperial Rule (or On Monarchy), Synesius of Cyrene offers some advise to the emperor Arcadius (r.395-408). More information about this speech, together with a brief summary, can be found here.
Throughout this speech, the word "Scythians" refers to the Tervingian Germans (who would later be known as Visigoths), whereas "king" refers to emperor.
The text is offered here in the translation by A. Fitzgerald. The four-digit numbers are page numbers of the Migne edition.
On Imperial Rule 20
  We made beneficence a stamp of kingship, passing in review again 'the giver of good gifts', 'the kindly one', names belonging also to God. Now let all these very properties and as many as were mentioned in their company before I promised to model the king in my discourse, be assigned to their right places, and let the image be completed. The chief of these ideas, perhaps, was that being able to originate good works he will not tire in this employment any more than does the sun when he gives his beams to plants and animals, for it is no labor to him to shine, inasmuch as he holds brightness in his being and is a fountain of light. And so the king, once that he has placed himself in this category of existence, will of himself order all, to whatever extent he reached that which is ruled over.
 Moreover, as for those who are near the throne, who are second to him alone and who are superior to the others, he will organize them by the kingly harmony of the soul, namely such men as are useful for each measure of the distributed power. From the very beginning the care of men will thus make greater progress in proportion as a greater number are engaged in the task.