While δεῖ can mean (s)he/it lacks, this form is frequently used IMPERSONALLY in the 3rd person singular to mean it is necessary. This construction is often complemented with an infinitive. For example:
- δεῖ ταῦτα ποιεῖν.
- It is necessary to do these things.
- νόμοι εἰσὶ καθ’ οὓς δεῖ τοὺς θεοὺς τιμᾶν.
- There are customs according to which it is necessary to honor the gods.
While δοκεῖ can mean (s)he/it seems, this form is frequently used IMPERSONALLY in the 3rd person singular to mean it seems (good). This construction is often complemented with a dative. For example:
- ὡς ἐμοὶ δοκεῖ…
- It seems to me (i.e. I think)…
- δοκεῖ τῇ βουλῇ καὶ τῷ δήμῳ…
- It seems best to the Boule and Demos (i.e., It is decreed by the Boule and Demos)…