ἡγούμενος τῶν ἡδονῶν ἀλλ' οὐκ ἀγόμενος ὑπ' αὐτῶν → of his pleasures he was the master and not their servant
neuter of a derivative from ἑκών; voluntariness: willingly.
ἑκούσιον: τό свободная воля Plat., Arst.