“Jesus ‘went up into the hills, and called to him those whom he desired; and they came to him’ (Mark 3:13).
On the one hand, we have the completely free decision of Jesus; on the other, the ‘coming’ of the Twelve, their ‘following’ Jesus. […] The absolute primacy of grace in the vocation is most perfectly proclaimed in the words of Jesus: ‘You did not choose me, but I chose you and appointed you that you should go and bear fruit and that your fruit should abide’” (John 15:16).