I came across this site:
http://ccel.org/ccel/richardson/fathers.toc.html
which has some of the very early writings of the church fathers, and I'm really amazed at how well preserved the teachings of modern Orthodoxy are.
Quotes like "Your fasts must not be identical with those of the hypocrites. They fast on Mondays and Thursdays; but you should fast Wednesdays and Fridays." http://ccel.org/ccel/richardson/fathers.viii.i.iii.html
I guess I really shouldn't be surprised, as that is what Orthodoxy is, the maintenance of tradition. What I would like is a recommendation for a book containing the earliest recognized teachings of the fathers, so that I might have something to show people who are hung up on the idea of sola scriptura that there are authentic extra-biblical sources in which one can see the foundation of the modern church being laid.
Thanks for your help!