Usually this candle is called The Shepherds Candle: emphasizing the joy of finding Christ and sharing this joy with others.
“And there were shepherds living out in the fields nearby ….An Angel of the Lord appeared to them, and the glory of the Lord shone around them. The Angel said to them, I bring you good news of great joy that shall be for all people. Today in the town of David a Savior has been born to you; he is Christ the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger. A great company of the heavenly host appeared with the angel, praising God and saying, Glory to God in the highest, and on earth peace to men on whom his favor rests. “
-Luke 2: 8-14