The mind is the most important thing in tennis.
"The past is a foreign country; they do things differently there."
听到了却没有亲眼见到,即使听得再多,也必有谬误;亲眼见到了却不能理解,即使记得再多,也必有错误;知道了却不去实际践行,就是知识再多,也必然困惑。