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 9
  Now my speech must go on to lead the king from out his palace, and, after his friends, to hand him over to the soldiers, second friends these; and further to make him descend to the plain and inspect his men, their arms, and their horses. There he will ride with the cavalry, charge with the infantry, arm himself heavily with the hoplites, maneuver with the targeteers, and hurl the javelin with the light-armed troops, enticing every man to living comradeship by association in their operations; so that not merely in semblance shall he call them fellow-soldiers. They will come to know him when he addresses them on the field, and will bear witness that the name is employed at the same time in virtue of his actions.
 Perchance you take it ill that we entail labor upon you, but be persuaded by me that toil attacks most lightly the body of a king, for toil vanquishes least of all a man who toils openly. Now when a king exercises his body, keeps the field, and spends his youth in armor, all the cities are spectators. For he draws the eyes of all present upon him, and no one can endure to look elsewhere when a king does anything conspicuously; every act of a king passing into a song rings in the ears of all men. And this custom is capable of bringing goodwill towards him in that the spectacle of a king is not a rare one to his soldiers, and his goodwill greatly strengthens the spirit of the troops.
 Now what royalty is more solid than that which is fortified by love, and what individual, however low his condition, is freer from fear or safer from treachery than that king whom his subjects fear not, bur for whom they fear?note[Plutarch, Aratus 25.7.] This soldierly race, however, is simple and noble, and is won over easily by sympathy. Even Plato calls his fighting race "guardians", and likens them most to the dog,note[Plato, State 375e, 376a, 376b.] a beast that distinguishes friend and foe by his knowledge and ignorance of them as the case may be. What could be more shameful than to be a king who is recognized only through the painters by the very men who war in his defense.
 The king will benefit by this close intercourse, not only because the army will surround him as one unified organism, but also because many of the incidents on these occasions are, some of them, an exercise in warlike affairs, and at the same time will be initiations, and preparations of a kind, for the function of command and awaken his ambition for great and serious tasks. It is no small advantage in active service that he can address by name a general, a commander of a legion, the commander of a squadron or of a brigade, or a standard-bearer, as the case may be; that he can call up and exhort any of the veterans from his knowledge of them, those I mean who have rank in each infantry or cavalry corps.
 Even Homer makes one of the gods take his station in the Achaean conflict and by a touch of his scepter fill  the young men "with mighty force", so that their spirit "longed still more to fight and to battle,"note[Homer, Iliad 13.60 and 13.74.] and they are unable to keep either their feet or hands quiet. Again the verse
Their feet beneath, their hands above, alike quiver with impatience,note[Homer, Iliad 13.75.]
signifies that they are self-bidden to dart about in deeds of battle. Now to my thinking a king might achieve this very result if he were to call on his men by name, and would thus rouse to ardor the man insensible to the trumpet's call, and incite the warrior yet more to the fray. For every man desires to toil under the watchful eye of the king. And the poet likewise seems to think that the king thus obtains an immense advantage both in war and in peace, for, noticing this first, the fact that even the common soldiers are known to the king has the greatest influence on the courage of these men,note[Homer, Iliad 4.231.] he has not only made Agamemnon call his soldiers by name, but even this leader, according to him, counsels his brother,note[Homer, Iliad 10.67.] in addition to this form of address, to distinguish each man by his patronymic and ancestral name, to honor all, and not to be overweening.
 Now honoring them is to speak to them in fair words, whenever he himself knows either that any good deed has been done by one of them, or that any success has fallen in his path. Observe Homer. He makes the king the eulogist of a man of the people, and who would not be lavish with his blood when the king has praised him? This benefit then will come to you from frequent contact with your troops, and moreover you will know their characters and their lives, and what post belongs to each in every contingency.
 Observe this also. The king is a craftsman of wars, just as the cobbler is a craftsman of shoes.note[Cf. Aristotle, Nicomachean Ethics 1101a.] The latter is laughable when he does not know the tools of his craft; how then shall the king understand how to use his tools, namely soldiers, when he does not know these tools?note[Xenophon, Cyropaedia 5.3.47.]