Doctrine Part 1

octrine can be defined as a teaching or instruction. So in this case, "they remained steadfast in the Apostles doctrine..."
Dedicated to the Apostles teachings and instruction. This not only means that they were dedicated to teaching, but also to being taught. This takes some humility.
It seems as if nowadays humility has become an undesirable trait. I believe it can also be stated that as the number of degrees one has attained increases, the humility of that person decreases. The more degrees one has, the more they think they know it all, therefore the less humble they are. I could see that in my life and I just have a two-year degree.
One thing that isn't taught in school is humility. Essentially, though, anyone under the teachings of the Apostles needs to earnestly seek and desire lowliness. For the Scriptures say, "...let each esteem others better than themselves" (Phil. 2:3).
Woah! I hope I receive a bunch of comments over that statement. I say that because this type of thinking is completely contrary to the way we are taught to think. We aspire to boast, brag, and exaggerate to others of ourselves, yet we're really deficient in probably many of those same characteristics that we flaunt.
In conclusion, this aspect of doctrine, which requires humility, is teachability, the ability to be taught - by whomever.