Literally, you can drink good water by digging a few wells, and you have to learn from more teachers to get high martial arts. (Note that "three" means many times. ) by extension, it is to study the same thing more and learn from multiple angles. If we only learn from one person, we may only learn one skill. Ask more people for advice, you can learn various skills and make up for the shortcomings from different angles. It can also be understood from the perspective of "three people must have a teacher" or the diversity of things.