The call of God in Christ comes with a divine power which does not need to wait upon accidental human circumstances; it can create the response it demands. And that response must be one of unconditional obedience, even to the point of sacrificing the means of livelihood and the closest natural ties, as many of St Mark's contemporaries must have known from experience (cf. [Mk] 10:28ff and Matt. 10:37-38 // Luke 14:26-27). The call is always to 'go after' Jesus in the path of discipleship (cf. [Mk] 3:13, 8:34, 10:52) and in this particular case the special vocation to which the converts were called was that of assisting Jesus in 'catching' men, i.e. drawing them out of the waters of this world into the net of the eschatological life of the age to come. We are to see that that was - and is - part of the vocation of all converts, even if all are not called, as these four were, to devote themselves exclusively and 'professionally' to it.