539 The Accusative may stand in apposition to a clause or sentence:

Ἔτλη θυτὴρ γενέσθαι θυγατρός, πολέμων ἀρωγν he endured to sacrifce his daughter, as an aid to war. A. AG. 236. τῶνδʼ ἔλεγχον τοῦτο μὲν Πῡθώδʼ ἰών πεύθου τὰ χρησθέντα as a test of this, first go to Pytho and inquire about the response. S. OT. 603.

Here belong expressions like προῖκα as a gift, freely, χάριν τινός as a favor to (for the sake of) some one, τεκμήριον as evidence, τὸ μέγιστον as the chief point, τὸ λεγόμενον as the saying is. When placed before the clause, such expressions may pass over into the use mentioned in 491 d.