The phrases ξὺν νόῳ (with understanding) and ξυνῷ (to the common) are very similar. Heraclitus is most likely playing on this words. No matter how much learning a person has, he will not have understanding if he turns aside to his own private world (B40, B129).
Many see the
reference to 'the divine one' as 'the divine law.' I do not think
this is what Heraclitus is saying. The Greek ἑνὸς τοῦ
θείου should be read as 'the divine
One,' meaning 'the one divine being.'