BWV 21: Ich hatte viel bekummernis

BWV 21: I had much trouble in my heart 

This cantata is a conversation between a man in despair and Jesus. I sang this in the Utah Baroque Ensemble several years ago. It's one of my favorites.

Ah, Jesus, my peace,
my light, where are You?
  - O soul behold! I am with you. -
With me?
Here is only darkest night.
  - I am Your faithful Friend,
that also watches in the darkness,
that might harbor dire mischief. -
Dawn then with Your radiance and light of comfort.
  - The hour approaches already,
    when your crown of battle
    will become a sweet refreshment.

BWV 20 Oh Eternity, Thou Thunderous Word

https://www.youtube.com/watch?v=yqGfDqsCvXQ

My favorite line from this one is "O Anfang sonder Ende" or "O Beginning without End".  Because we are constantly living in the beginning of times, ideas, possibilities.