Plato the writer on grammata as play, in Phaedrus 276c–d, a little after talking about the so-called “Adonis gardens” which thrived in a few days and which he compares to serious farming:

Socrates: — Whoever understands what is just, beautiful and good, are we going to say that he is less intelligent concerning his seeds than the farmer?
Phaedrus: — Not at all!
Socrates: — He is not seriously going to write this stuff in black water, using his seed-stick to sow with words unable to defend themselves and argue back, unable even to teach the truth properly.
Phaedrus: — Fat chance!
Socrates: — Really! But what is more likely is that it is gardens that he will play at seeding with letters. He will write, if he pleases, to amass memories for himself, in the event he reaches forgetful old age, and for anyone who follows the same path.

ΣΩ. Τὸν δὲ δικαίων τε καὶ καλῶν καὶ ἀγαθῶν ἐπιστήμας ἔχοντα τοῦ γεωργοῦ φῶμεν ἧττον νοῦν ἔχειν εἰς τὰ ἑαυτοῦ σπέρματα;
ΦΑΙ. ἥκιστά γε.
ΣΩ. οὐκ ἄρα σπουδῇ αὐτὰ ἐν ὕδατι γράψει μέλανι σπείρων διὰ καλάμου μετὰ λόγων ἀδυνάτων μὲν αὑτοῖς λόγῳ βοηθεῖν, ἀδυνάτων δὲ ὶκανῶς τἀληθῆς διδάξαι.
ΦΑΙ. Οὔκουν δὴ τό γ᾽εἰκός.
ΣΩ. Οὐ γάρ: ἀλλὰ τοὺς μὲν ἐν γράμμασι κήπους, ὡς ἔοικε, παιδιᾶς χάριν σπερεῖ τε καὶ γράψει, ὃταν [δὲ] γράφῃ, ἑαυτῷ τε ὑπομνήματα θησαυριζόμενος, είς τὸ λήθης γῆρας ἐὰν ἳκηται, καὶ παντὶ τῷ ταὐτὸν ἴχνος μετιόντι….
[text from Moreschini, Platon. Phèdre (Paris: les Belles-Lettres, 2002)]