This is the third night of candle lighting and those three candles are starting to drive the darkness back. We can see by them now. The first candle was lit on the 17th, the candle for Wisdom. The second, the Lord candle was lit on the 18th. The third candle is for the Rod and Root of Jesse. Traditionally these are both sung on the same day. We like to separate them so that we can ponder each one a little longer.

The Rod of Jesse and the Root of Jesse are two sides of the Messiah. He will be the Jewish Messiah, coming through the lineage of Jesse. He will be a branch on that family tree. Isaiah uses the Hebrew word netzer for branch in Chapter 11:

A shoot will come up from the stump of Jesse;
    from his roots a Branch will bear fruit.
The Spirit of the Lord will rest on him—
    the Spirit of wisdom and of understanding,
    the Spirit of counsel and of might,
    the Spirit of the knowledge and fear of the Lord—
 and he will delight in the fear of the Lord.

He will not judge by what he sees with his eyes,
    or decide by what he hears with his ears;
but with righteousness he will judge the needy,
    with justice he will give decisions for the poor of the earth.

As I understand it, the word netzer+the feminine ending designated by the letter Tav, is the word Nazaret (or Nazareth). This is a sign to the Jewish people. Your God will deliver you. He is sending you a Branch of Jesse's tree to save you.

O come, Thou Rod of Jesse's stem
From every foe deliver them
That trust thy mighty pow'r to save,
And give them victory o'er the grave.

Rejoice! Rejoice! Emmanuel shall come to thee, O Israel!

The Root of Jesse's Tree is the Source, God Himself. Messiah will be Before All Ages, the Root. This is Messiah for the Gentiles. Those who do not understand the lineage come to Messiah because He is also the Root. God of all. He will be a banner for all peoples, calling them to Himself. And this Root will also reclaim His lost remnant in the same way, calling them to their Source.

In that day the Root of Jesse will stand as a banner for the peoples; the nations will rally to him, and his resting place will be glorious. In that day the Lord will reach out his hand a second time to reclaim the surviving remnant of his people from Assyria, from Lower Egypt, from Upper Egypt, from Cush, from Elam, from Babylonia, from Hamath and from the islands of the Mediterranean. ~Isaiah 11: 10-11

And so tonight and tomorrow, we call to Him who is the Beginning and the End. Come soon!

O come, Thou Root of Jesse's tree,
An ensign of Thy people be;
Before Thee rulers silent fall;
All peoples on Thy mercy call.

Rejoice! Rejoice! Emmanuel shall come to thee, O Israel!