Letter 36: Procopius says small offerings can still show gratitude for great benefactions.

The experience of your gift moves those who know it to admiration, and its fame moves everyone else. Both make me hold your benefaction forever unwritten in my debt. When I am admired because I have become the servant of such good things for my fatherland, I refer the cause of those good things back to you in memory. For that reason I am always bolder than is fitting when I bring small things to you. There is nothing surprising in that. People who burn incense to the gods do not display gratitude according to the gods' worth, but according to their own ability. So too, with the things offered to you, the greatest and the least have the same power when measured against the benefaction.

Ἠλίαι Τῆς ὑμετέρας δωρεᾶς ἡ μὲν πεῖρα τοὺς ἐγνωκότας, ἡ δὲ φήμη τοὺς ἄλλους εἰς θαῦμα κινεῖ, ἐμὲ δὲ ἀμφότερα πρὸς τὸ ἀνάγραπτον ἐσαεὶ τὴν ὑμετέραν ἔχειν εὐεργεσίαν. καὶ θαυμαζόμενος ἐφ' οἷς τοιούτων ἀγαθῶν ὑπηρέτης γέγονα τῇ πατρίδι, εἰς ὑμᾶς ἀνάγω τῇ μνήμῃ τῶν ἀγαθῶν τὴν αἰτίαν. ὅθεν, ἀεὶ παρὰ τὸ προσῆκον παρρησιάζομαι τὰ μικρὰ προσάγων ὑμῖν· καὶ θαυμαστὸν οὐδέν· οὐδὲ γὰρ οἱ τοῖς θεοῖς λιβανωτὸν ἐπιθύοντες πρὸς ἀξίαν τὴν χάριν, πρὸς δὲ δύναμιν τὸ δοκεῖν εὐγνώμονες ἐπιδείκνυνται. καὶ ἐπὶ τῶν ὑμῖν προσαγομένων τὰ μέγιστα τοῖς ἐλαχίστοις τὴν αὐτὴν ἔχει δύναμιν πρὸς τὴν εὐεργεσίαν μετρούμενα.