From a sermon by Martin Luther on the First Sunday of Advent, 1533.

Zechariah 9:9 Behold Your King comes to you, just and having salvation; lowly, and riding upon an ass.

Yes, truly, He will be a king, but a poor and wretched king.  He leaves to other kings’ pomp, castle, palaces, gold and wealth; lets them eat and drink, dress and build more daintily than other folks; but the craft which Christ the poor beggar-king knows, they do not know.

He helps not against one sin, but against all my sin; and against the world’s sin.  He comes to take away not only sickness, but death; and not my death only, but the whole world’s death. Do not be offended by his lowly advent; shut your eyes and open your ears, and perceive not how he rides so beggarly, but hearken to what is said and preached about this poor king. He comes riding on an ass like a beggar having neither saddle nor spurs.  This King, will take sin from us, strangle death, endow us with eternal holiness, eternal bliss, and eternal life, this cannot be sin.  Therefore, we must hear and believe.