It is simply impossible to discover that hypnosis exist. All the discoveries and inventions are made using logic. You simply cannot use logic to know that human brain can be hypnotized, unless somebody told you this. My theory is that earthlings were genetically engineered as a race of slaves who can be brainwashed in order to become obedient slaves. Therefore the 1% of elite must be aliens who are controlling the rest of the 99% slaves. Since the aliens have evolved their knowledge about how to control slaves, they quit obvious slavery and substituted it with ideologies such as socialism and capitalism. I know it sounds incredible, but it's still plausible, because can explain all the shit happening in 2000 years.