From my grandfather:
Not to waste time on public schools, but rather make use of good teachers at home — and also to know when it is necessary to spend money.
Greek Text & Notes
Παρὰ τοῦ προπάππου τὸ μὴ εἰς δημοσίας διατριβὰς φοιτῆσαι καὶ τὸ ἀγαθοῖς διδασκάλοις κατ̓ οἶκον χρήσασθαι καὶ τὸ γνῶναι ὅτι εἰς τὰ τοιαῦτα δεῖ ἐκτενῶς ἀναλίσκειν.
Παρὰ τοῦ προπάππου
From my grandfather
τὸ μὴ εἰς δημοσίας διατριβὰς φοιτῆσαι
Diatripbas here has the sense of “wasting time” (see LSJ II).
The infinitive phoitesai shows the result: “esp. of objects of commerce, to come in constantly or regularly”
Not to waste time regularly attending public [schools]. Schools is implied by the next clause where the wasting is contrasted with good teachers at home.
καὶ τὸ ἀγαθοῖς διδασκάλοις κατ̓ οἶκον χρήσασθαι
And to make use of good teachers at home.
The dative marks “good teachers” as the object of the thing made use of (chresasthai).
καὶ τὸ γνῶναι ὅτι εἰς τὰ τοιαῦτα δεῖ ἐκτενῶς ἀναλίσκειν.
καὶ τὸ γνῶναι
And to know
The content of the knowledge
τὰ τοιαῦτα δεῖ ἐκτενῶς ἀναλίσκειν.
Those things it is necessary to extending spend
The infinitive completes “dei”.