§ 34.6. =Personal and Epistolary Intercourse.=--From the very earliest times the Christian churches of all lands maintained a regular communication with one another through messengers or itinerating brethren. The _Teaching of the XII. Apostles_ furnishes the earliest account of this: Any one who comes from another place in the name of the Lord shall be received as a brother; one who is on his journey, however, shall not accept the hospitality of the church for more than two, or at furthest than three days; but if he chooses to remain in the place, he must engage in work for his own support, in which matter the church will help him; if he will not so conduct himself he is to be sent back as a χριστέμπορος, who has been seeking to make profit out of his profession of Christ. The Didache knows nothing as yet of the letters of authentication among the earlier messengers of the church which soon became necessary and customary. As a guarantee against the abuse of this custom such συστατικαὶ ἐπιστολαί (2 Cor. iii. 1) had come into use even in Tertullian’s time, who speaks of a _Contesseratio hospitalitatis_, in such a form that they were understood only by the initiated as recognisable tokens of genuineness, and were hence called _Litteræ formatæ_, or γράμματα τετυπωμένα. The same care was also taken in respect of important epistolary communications from one church to another or to other churches. Among these were included, _e.g._ the Synodal rescripts, the so-called γράμματα ἐνθρονιστικά by which the newly-chosen bishops intimated their entrance upon office to the other bishops of their district, the _Epistolæ festales_ (paschales) regarding the celebration of a festival, especially the Easter festival (§ 56, 3), communications about important church occurrences, especially about martyrdoms (§ 32, 8), etc. According to Optatus of Mileve (§ 63, 1): “_Totus orbis_” could boast of “_comnmercio formatarum in una communionis societate concordat_.”