So to be exact, it's Euclid saying "there is no royal road to geometry". So Euclid means that a king for example couldn't spend a bunch of money to acquire an understanding of geometry, rather, just like a peasant he would have to go through the effort of thought to arrive at a proficiency with the ideas. It's not a saying that means there is no logically coherent path or something like that, it's a socially concerned comment that wealth or power won't necessarily give you a shortcut to true wisdom and knowledge.