Why were only shepherds and Magi called by God to the manger?  They were called because they were so well disposed to receive God's graces and attuned to hear His call.  Two virtues in particular stand out in these privileged guests of the Nativity: prayerfulness and generosity.  Mother Mary Bosco describes these dispositions, and relays helpful suggestions for imitating the prayerfulness and the generosity of the shepherds and kings in fulfilling the Will of God.