"When the student is ready, the teacher will appear." What do you think it means? Consider: How does the teacher know when the student is ready? Have you ever been the student seeking the teacher or the teacher seeking the student. Life always has us in the roles of both.
When we're young, we're the student of our parents and when we grow up, we become the first teachers of our children.
When we're young, we learn in school and when we grow up, we become the teachers.
The concept comes from the more famous quote, "you can lead a horse to water, but you can't make him drink.", the same idea is true with people, you can try to teach people lessons, but you can't make them learn.
However, when someone truly wants to learn, they can always, easily find a person or place to learn from.
Try to teach a 5 year old Karate and this quote suddenly makes a lot of sense. It is impossible, unless the child wants to learn.
And if a child quits, they may be ready to learn later in life, and then even if that school from when they were 5 is closed and gone, they will find another Karate school on a different block, It will appear without even looking very hard, because it is in the forefront of the mind.
It was there all along, but the person was not open to it.