Plato Epistles 9

[357] 357d
  Plato to Archytas ¹ of Tarentum wishes well-doing.
  Archippus and Philonides and their party have arrived, 357e bringing us the letter which you gave them, and also reporting your news. Their business with the city they have completed without difficulty—for in truth it was not at all a hard task; and they have given us a full account of you, telling us that you are somewhat distressed at not being able to get free from your public engagements.

[358] Now it is plain to almost everyone that the pleasantest thing in life is to attend to one’s own business, 358 358a especially when the business one chooses is such as yours; yet you ought also to bear in mind that no one of us exists for himself alone, but one share of our existence belongs to our country, another to our parents, a third to the rest of our friends, while a great part is given over to those needs of the hour with which our life is beset. And when our country itself calls us to public duties, it were surely improper not to hearken to the call ² ; for to do so will involve the further consequence of leaving room 358b to worthless men who engage in public affairs from motives that are by no means the best.
  Enough, however, of this subject. We are looking after Echecrates now and we shall do so in the future also, for your sake and that of his father Phrynion, as well as for the sake of the youth himself.