Plato, Laws 769d

τί οὖν; ἆρʼ οὐ τοιοῦτον δοκεῖ σοι τὸ τοῦ νομοθέτου βούλημʼ εἶναι; πρῶτον μὲν γράψαι τοὺς νόμους πρὸς τὴν ἀκρίβειαν κατὰ δύναμιν ἱκανῶς· ἔπειτα προϊόντος τοῦ χρόνου καὶ τῶν δοξάντων ἔργῳ πειρώμενον, ἆρʼ οἴει τινὰ οὕτως ἄφρονα γεγονέναι νομοθέτην, ὥστʼ ἀγνοεῖν ὅτι πάμπολλα ἀνάγκη παραλείπεσθαι τοιαῦτα, ἃ δεῖ τινα συνεπόμενον ἐπανορθοῦν, ἵνα μηδαμῇ χείρων, βελτίων δὲ ἡ πολιτεία

Well then, do you not think that the purpose of the lawgiver is similar? He purposes, first, to write down the laws, so far as he can, with complete precision; next, when in the course of time he puts his decrees to the test of practice, you cannot suppose that any lawgiver will be so foolish as not to perceive that very many things must necessarily be left over, which it will be the duty of some successor to make right, in order that the constitution and the system of the State he has organized may always grow better,