But angels show up in the midst of the pasture, announcing Jesus' birth in all splendor and majesty, triumphantly singing a pronouncement of peace on earth and goodwill to all. So the shepherds go into town to find the stable that housed the King of Kings (what else were they going to do after angels show up and give them directions?--and what else but a message from angels would convince them to go look in a manger for the Messiah?). They were presumably the first to see the infant besides Mary and Joseph. And then they go and spread the news of what they have seen.
It so happened that afterward the boys and I watched the 1968 Rankin-Bass version of "The Little Drummer Boy." I don't remember actually seeing it when I was young. Less religious shows like Frosty and Rudolph probably pushed it out of a time slot--not to mention it's a bit cheesy. But it's a nice story about a boy who hates humanity because of the death of his parents, but finds a whole heart after following the Magi to the stable where the Christ Child is. There, amongst the shepherds and Magi (who show up together in the story), the little drummer boy shares his only gift--a song--with the newborn King.
The writer of our Advent devotional pointed out that the lambs that were sacrificed in the temple in Jerusalem were raised in Bethlehem. The shepherds who the angels heralded went to the stable to visit He who would be the final sacrificial Lamb. In the manger they beheld the greatest sacrifice; they were present at His birth to praise the Lamb.
As we wait in Advent, let us remember that Jesus came for everyone--shepherd and magi alike. He doesn't care if we bring Him frankincense or percussion song. He cares that we bring Him our heart--that we bring Him the best (and worst) of us. He invites us to set at the foot of His manger and praise the Son of God, the Son of man.