Laudator Temporis Acti

Constantine Porphyrogenitus, De Administrando Imperio. Greek Text Edited by Gy. Moravcsik, English Translation by R.J.H. Jenkins. New, Revised Edition (Washington: Dumbarton Oaks Center for Byzantine Studies, 1967; rpt. 1993), p. 75 (from chapter 13 of the treatise):

For each nation has different customs and divergent laws and institutions, and should consolidate those things that are proper to it, and should form and develop out of the same nation the associations for the fusion of its life. For just as each animal mates with its own tribe, so it is right that each nation should marry and cohabit not with those of other race and tongue but of the same tribe and speech. For hence arise naturally harmony of thought and intercourse among one another and friendly converse and living together; but alien customs and divergent laws are likely on the contrary to engender enmities and quarrels and hatreds and broils, which tend to beget not friendship and association but spite and division.

Greek text (id., p. 74):

Ἕκαστον γὰρ ἔθνος διάφορα ἔχον ἔθη καὶ διαλλάττοντας νόμους τε καὶ θεσμοὺς ὀφείλει τὰ οἰκεῖα κρατυνεῖν καὶ ἀπὸ τοῦ αὐτοῦ ἔθνους τὰς πρὸς ἀνάκρισιν βίου κοινωνίας ποιεῖσθαι καὶ ἐνεργεῖν. Ὥσπερ γὰρ ἕκαστον ζῷον μετὰ τῶν ὁμογενῶν τὰς μίξεις ἐργάζεται, οὕτω καὶ ἕκαστον ἔθνος οὐκ εξ ἀλλοφύλων καὶ ἀλλογλώσσων, ἀλλ’ ἐκ τῶν ὁμογενῶν τε καὶ ὁμοφώνων τὰ συνοικέσια τῶν γάμων ποιεῖσθαι καθέστηκε δίκαιον. Ἐντεῦθεν γὰρ καὶ ἡ πρὸς ἀλλήλους ὁμοφροσύνη καὶ συνομιλία καὶ προσφιλὴς συνδιατριβὴ και συμβίωσις περιγίνεσθαι πέφυκεν· τὰ δε ἀλλότρια ἔθη καὶ διαλλάττοντα νόμιμα ἀπεχθείας μᾶλλον καὶ προσκρούσεις καὶ μίση καὶ στάσεις εἴωθεν ἀπογεννᾶν, ἅπερ οὐ φιλίας καὶ κοινωνίας, ἀλλ’ ἔχθρας καὶ διαστάσεις φιλεῖ ἀπεργάζεσθαι.

Related post: Flocking Together.