περὶ οὐδὲν γὰρ οὕτως ὑπάρχει τῶν ἀνθρωπίνων ἔργων βεβαιότης ὡς περὶ τὰς ἐνεργείας τὰς κατ' ἀρετήν → since none of man's functions possess the quality of permanence so fully as the activities in conformity with virtue
calmly: P. and V. ἡσυχῆ, ἡσύχως (rare P.), Ar. and V. ἀτρέμα (rare P.), Ar. and P. ἀτρέμας.
peacefully, without care: P. and V. ἀπραγμόνως (Euripides, Fragment).