Innovations
The main realizations I had about theatre through this course are its development through innovators. The modern musical theatre show we see today is only a result of people who broke away from traditional constrictions and conventions of theatre and revolutionized aspects of theatre. Innovations through each age is what allows us to enjoy the theatre that we love to see today.
Not just acting styles has allowed for these changes. Everything from set design to the sociological aspects of societies has influenced what we see on stages today.
Italian designers such as Serlio helped to develop perspective scenery on stage and allow for new technologies in set movement. Our standard indoor theatre buildings with the proscenium arch as taken extreme changes since the times of the ancient Greeks and their huge outdoor ampitheatre.
Even the topics of shows has changed- whereas the ancient Greeks mainly wrote about god and dieties, Medeival people wrote about religion as well; in fact, the initial main purpose of theatre in this time was to affirm and establish faith throughout the society. Fast forward to 2011, and we have musicals ridiculing the Morman religion (in a charming way). 
It took ALOT to create the genre of musical theatre that we love so much- it has really only come to develop in the last century. Although many things have changed since the time of the Greeks, many elements have contiued in some way. This can be seen with elements such as the stock characters in the comedies of ancient Rome. These were then rediscovered in the renaissance, and playwrights such as Moliere used this same type of stock characters in commedia de'arte.  Now, it is carried over into countless shows such as A Funny Thing Happened on the Way to the Forum.
The Florentine Camarata, in an attempt to recreate Greek and Roman theatre, started developing opera which was a great influence on the development of musical theatre.
In short, I made the connection that musical theatre didn't just spring up out of nowhere from talented people such as Cole Porter, Irving Berlin, and the Gershwin brothers.  Musical theatre is the product of human innovations through centuries and centuries, and is still a work in progress today. 
http://www.youtube.com/watch?v=C2ODfuMMyss
http://www.youtube.com/watch?v=PDZC5UOPb6E
http://www.youtube.com/watch?v=s62MrU8mHx4