If you are to become efficient teachers...

Because of my vocation as a high school English teacher, I've read a lot of great introductions.  I love Melville's take-charge attitude in line one of Moby Dick: "Call me Ishmael." Like Ahab, he offers no alternative.  F. Scott Fitzgerald's great novel proffers this great beginning: "In my younger and more vulnerable years my father gave me some advice that I’ve been turning over in my mind ever since."
  
C.F.W. Walther, crafted this perfect introduction in his First Evening lecture on September 12, 1884. "If you are to become efficient teachers in our churches and schools..." 

What do I need to know?  What kind of cruel tease is this?  How can Walther not tell me how I can become an efficient teacher?  Fret not, the first president of the Lutheran Church Missouri Synod continues:

...it is a matter of indispensable necessity that you have a most minute knowledge of all doctrines of the Christian revelation. However, having achieved such knowledge, you have not yet attained all that is needed. What is needed over and above your knowledge of the doctrines is that you know how to apply them correctly. You must not only have a clear apperception of the doctrines in your intellect, but all of them must have entered deeply into your heart and there manifested their divine, heavenly power.

If you want to become a teacher, if you are already a teacher, I urge you to read the lecture and those that follow.  Walther's insights on the doctrines of Law and Gospel are more practical than any teacher's edition text.  Here are several snippets from this lecture that clarify the important distinction found in Law and Gospel:  

The Law offers us food, but does not hand it down to us where we can reach it. It offers us salvation in about the same manner as refreshments were offered to Tantalus in the hell of the pagan Greeks. It says to us indeed: “I will quench the thirst of your soul and appease your hunger.” But it is not able to accomplish this because it always adds: “All this you shall have if you do what I command.” The Law offers us food, but does not hand it down to us where we can reach it. It offers us salvation in about the same manner as refreshments were offered to Tantalus in the hell of the pagan Greeks. It says to us indeed: “I will quench the thirst of your soul and appease your hunger.” But it is not able to accomplish this because it always adds: “All this you shall have if you do what I command.”

 Over and against this note the lovely, sweet, and comforting language of the Gospel. It promises us the grace of God and salvation without any condition whatsoever. It is a promise of free grace. It asks nothing of us but this, “Take what I give, and you have it.” That is not a condition, but a kind invitation.

When the Law has laid us low, we can cheerfully raise our heads again because besides the Law we have another doctrine which proposes to us no demands of any kind. Were we to ask Christ, “What is expected of me in order that I may be saved?” He would answer: “No works; I have done all the works that had to be done. You need not drink one drop of the cup that I had to drink.”