Theoretical knowledge is a path fraught with thorns. It is a path that requires perseverance and perseverance, along with contemplation, extracting thought, and deducing general rules from observations and experiences, then applying the rule to know its validity, and correcting it if it turns out to be an error, which requires a long time that may not be measured by the age of the individual, but rather by the lifespan of the individual. Generations and generations.
The science and knowledge that humanity has achieved today is the fruit of all of humanity since the dawn of civilization. It is the history of human thought, which has passed - and continues to pass - two stages, a stage of monopoly and a stage of permissibility. In the stage of monopoly, an individual, and most often a few individuals, keeps the secrets of knowledge that he either obtained himself, or took from his teacher... and so on, so that knowledge is passed down generation after generation. Therefore, this type of education was a secret, its schools were secret, and its teachings were "esoteric."
As for the other type, it is the published permissible teachings. Don't you see how it preserves its secrets from the research of the atom, the atomic explosion, and the making of the atomic and hydrogen bombs? It is even easier than this. Do you not see how industrial companies keep the "secret of craftsmanship" so that no one competes with them in the market? It is no wonder that secret schools arose in the past and monopolized knowledge and the subsequent influence and authority.