Takuan Sōhō had a unique insight into how people learn.

A beginner knows nothing about posture or position of the sword, so there is no dwelling on body or mind; if someone attacks him, he scrambles to deal with it mindlessly. As he learns various things, however —physical posture, how to wield the sword, where to place the mind —his mind dwells on various points; if he tries to strike someone, what with one thing and another, he is exceptionally handicapped.

When he has practiced daily for months and years, finally his posture and way of wielding the sword become mindless, like he was at first when he didn’t know anything and there was nothing to it. This is the frame of mind in which the beginning and the end are the same. If you count from one to ten and over again, then one and ten are next to one another. In the musical scale too, when you go from A to G from one octave to the next, then A and G are next to one another; the lowest and the highest come to resemble each other.

Takuan Sōhō

While this is a long quote at first glance, Takuan manages to boil down a process that takes a lifetime into two paragraphs. According to Zen in the Martial Arts, Bruce Lee was a huge fan of this quote, and used it with his students.