Let's Talk About It With Jenny White/ The Willie Lynch Letter, is it real?

This letter is said to have been delivered by Willie Lynch on the bank of the James River in the colony of Virginia. He was a British slave owner in the West Indies and was invited to the colony to teach his methods to slave owners there. 

He was supposedly asked about his full-proof method of keeping his slaves in line. Altho, this letter over time has been said not to be true and that it does not exist, 

Who really knows whether this letter was written by a man named Willie Lynch for the purpose of keeping slaves in line or did he watch them work and learned to read with accuracy their state of mind?