Plato, Laws 792a

αὐτοῖς ἐν τῇ προσφορᾷ τεκμαίρονται· οὗ μὲν γὰρ ἂν προσφερομένου σιγᾷ, καλῶς οἴονται προσφέρειν, οὗ δʼ ἂν κλάῃ καὶ βοᾷ, οὐ καλῶς. τοῖς δὴ παιδίοις τὸ δήλωμα ὧν ἐρᾷ καὶ μισεῖ κλαυμοναὶ καὶ βοαί, σημεῖα οὐδαμῶς εὐτυχῆ· ἔστιν δὲ ὁ χρόνος οὗτος τριῶν οὐκ ἐλάττων ἐτῶν, μόριον οὐ σμικρὸν τοῦ βίου διαγαγεῖν χεῖρον ἢ μὴ χεῖρον. ὀρθῶς λέγεις. ὁ δὴ δύσκολος οὐδαμῶς τε ἵλεως ἆρʼ οὐ δοκεῖ σφῷν

If it remains silent when the thing is offered, they conclude that it is the right thing, but the wrong thing if it weeps and cries out. Thus infants indicate what they like by means of weepings and outcries—truly no happy signals!—and this period of infancy lasts not less than three years, which is no small fraction of one’s time to spend ill or well. You are right. When a man is peevish and not cheerful at all, do you not regard him