The text presented here, a letter that accompagnied the gift of an astrolabe, was sent to Pylaemenes, an important military leader whom Synesius had met in Constantinople. It is a brief essay in which Synesius advises politicians to study the sciences (which the author, as always, calls "philosophy"). Synesius also mentions several improvements to the instrument; the model sent to Pylaemenes appears to have been some sort of prototype.
The text is offered in the translation by A. Fitzgerald.
On an Astrolabe 9-13
 Now you seem about to restore to us this duality of force, for you are entrusted with the management of public affairs, and at the same time you believe in the cultivation of philosophy. Strike then, as it is a fair struggle in which you are engaged, on behalf of us and the Muses, so that no one may expel them from the market-place or the camp as unpractical and unworkable, as of no use for actions to be fought under the open sky, but merely pretty things for children to play with and to babble about.
 It is fitting that everyone of us should stretch out a hand to your assistance in so far as the power within him lies. Thus you would be fashioned a wise man indeed, not a half-fulfilled or mutilated sage, as must be the case whenever a man is upheld by his natural bent only. Well were it for a state to be governed by such men as this, and we should be the gainers thereby, courting honor for philosophy from men, while at the same time we should live a worthy moral life.
 So a probability might come about quite contrary to that which was mentioned recently, when we were saying that the tribe of sophists laid their snares for the ignorance of the multitude, and that as a result of this the legitimate sons of philosophy came to have less repute than the superstitious and fraudulent. But when those who hold the reins of government, and have the affairs of the cities in their grasp, are not of the people, but possess intellectual culture, they will quickly make the distinction between the legitimate and illegitimate philosopher, and no longer will it be difficult for the common people to learn what sort of deception has been practiced upon them. There will be no need to address them on the matter; all that is necessary is to brand the charlatans with their own obscurity.
 It is, moreover, a law of Nature that the class which leads should be admired, by reason of the subjection of the governed. Nay, even now, mostly for the very drollness of things the multitude follows the long-haired sages and all such brazen creatures, and esteems them something extraordinary, and the other more variegated sorts of sophists they all but worship and stand in awe of, particularly those who stride about with a mighty staff, and clear their throats before they speak.
 So you will come to the rescue of philosophy in misfortune, but you will not be her accuser, for she is guilty in nothing. The right thing seems to have taken place, and you will further this in the direction of what is better and more fitting, as soon as the study of philosophy has gained a stronger hold upon you. Nay, even now you have nobly taken up the common fight, barking back at these dogs, and undertaking to fortify our Decelea.note[During the Peloponnesian War, the Spartans fortified this town, and used it to attack Athens. Synesius wants a philosophically-minded Pylaemenes to destabilize the unphilosophical government.]