Here is a model letter from Libanius (1 in the Loeb; 15 in the Foerster Teubner). Yes, Libanius is (allegedly) writing a letter about how he is no longer going to write letters.
1 To Zenobius
“I have decided to fight silence with silence. Indeed, I do still understand that this penalty falls short of the wrongs done to me: It is not the same for me to be bereft of your letters and my letters to fail to go to you. The harm I suffer is as much greater than my vengeance as your letters are better than mine.”
- Ζηνοβίῳ
Σιγῇ τὴν σιγὴν ἔγνωμεν ἀμύνασθαι. καίτοι γε ἠπιστάμην λειπομένην τῶν ἀδικημάτων τὴν δίκην. οὐ γὰρ ἴσον ἦν ἐμὲ σῶν ἀποστερεῖσθαι γραμμάτων καὶ σοὶ <τὰ>1 παρ᾿ ἡμῶν μὴ φοιτᾶν. ἀλλ᾿ ὅσῳ καλλίω τὰ σά, τοσούτῳ μείζων ἡ βλάβη τῆς τιμωρίας.
“I have decided to fight silence with silence. Σιγῇ τὴν σιγὴν ἔγνωμεν ἀμύνασθαι.
ἔγνωμεν activ aorist plural first
It must be we have decided… I think…