After the substs. ὑπερβολή and ἔλλειψις, we should expect ταῦτα δ᾽ ἐστὶ τὸ μείζω τε καὶ σμικρότερα γίγνεσθαι, but the sentence is const. as though replying to the question καὶ πῶς ἄλλως ἄξια τὰ ἡδέα πρὸς τὰ λυπηρά, ἀλλ᾽ ἢ ὑπερβάλλοντα ἄλληλα καὶ ἐλλείποντα;
ἡδύ: we should have expected ἡδὺ καὶ λυπηρόν, but, as the words stand, we must regard καὶ λυπηροῦ, which follows, as an afterthought.