Originally Posted by
Dee74 
[I]The Ancient One: You cannot beat a river into submission. You have to surrender to its current, and use its power as your own.
Strange: I control it by surrendering control? That doesn’t make any sense.
There may be truth in both of these responses, and it's possible that both metaphors are extremes. A canoeist surrenders to the river. He cannot overpower it, but combines his skills with the current. Skiers don't conquer the mountain. They adapt as the slope gets steeper.
This is what Dr. Strange learned to do, and he added his skills to the ancient one's, and then he combined that with mysticism to master an even bigger challenge. Mordo is much more rigid, even far more than the skeptical Dr. Strange, and Wong is probably somewhere in between.