This passage is difficult to render alike from the variety of readings and the obscurity of each.  I have endeavoured to represent the force of the Greek ἐκ τῆς ἑτοιμασίας τοῦ ἐφ᾽ ἡμῖν, understanding by “τὸ ἐφ᾽ ἡμῖν,” practically, “our free will.”  cf. the enumeration of what is ἐφ᾽ ἡμῖν, within our own control, in the Enchiridion of Epicetus, Chap. I.  “Within our own control are impulse, desire, inclination.”  On Is. vi. 8, “Here am I; send me,” St. Basil writes, “He did not add ‘I will go;’ for the acceptance of the message is within our control (ἐφ᾽ ἡμῖν), but to be made capable of going is of Him that gives the grace, of the enabling God.”  The Benedictine translation of the text is “per liberi arbitrii nostri præparationem.”  But other readings are (i) τῆς ἑτοιμασίας αὐτοῦ, “the preparation which is in our own control;” (ii) τῆς ἑτοιμασίας αὐτοῦ, “His preparation;” and (iii) the Syriac represented by “arbitrio suo.”