What advice did martina navratilova give when playing a volley

Martina Navratilova stated that the wrist needs to be in a neutral position. You should have a firm wrist, but not a tilted wrist, as a tilted wrist limits you. Having a tilted wrist causes you to make mistakes and you cannot hit the ball. If you tilt your wrist, the face of the racket actually moves so that it’s facing you more, and that means that you will be forced to hit it cross-court. If you want to go down the line, you move your wrist, and that means you lose power. If you keep the wrist flat, you have much more power.

it affected it because the kingdoms (with trade) slowly got richer and richer.