Rambam-How to Teach Maaseh Merkavah and Maaseh Breishis- Yisodei hatorah perek 4 halacha 11

The Rambam continues his discussion of the differences between Maaseh Merkavah and Maaseh Breishis (Metaphysics and Physics). He says,


ומה בין ענין מעשה מרכבה לענין מעשה בראשית. שענין מעשה מרכבה אפילו לאחד אין דורשים בו אא"כ היה חכם ומבין מדעתו מוסרין לו ראשי הפרקים. וענין מעשה בראשית מלמדין אותו ליחיד אע"פ שאינו מבין אותו מדעתו ומודיעים אותו כל מה שיכול לידע מדברים אלו. ולמה אין מלמדין אותו לרבים. לפי שאין כל אדם יש לו דעת רחבה להשיג פירוש וביאור כל הדברים על בוריין


"What is the difference between the subject of Maaseh Merkavah and the subject of Maaseh Breishis. The subject of Maaseh Merkavah is not allowed to be expounded unless the person is wise and about to undertand through his own knowledge and then, only the basic principles are allowed to be told over. The subject of Maaseh Breishis can be taught one-on-one even though the person can not understand it on their own and it can be made known to this person as much as possible. However, why can't (Maaseh Merkava) be taught to the masses? This is because not every man is equipped with a broad mind to attain the correct understanding of this subject."

The laws of teaching Maaseh Merkavah and Maaseh Breishis can tell us a great deal about their subject matter. The fact that Maaseh merkavah can only be taught to a wise person that can understand the subject matter on his own and the specifics of the subject matter are not allowed to be passed on is very telling. Maaseh Merkavah must contain information that is so complex and difficult to understand that the Rabbis were worried that it could easily be misunderstood. Not only must they have been afraid of this misunderstanding, but also the outcome of this misunderstanding. Therefore, only someone who can figure the subject matter out on their own is allowed to even be told the general ideas found within this category of subjects. This is Metaphysics. Metaphysics is concerned with explaining the fundamental nature of being and the world. In Judaism, this subject is very abstract and has to do with G-D and spirituality. This is why Maaseh Merkavah can not be taught to just anyone, because it has to do with very abstract ideas and some of them are unrelated to the physical world.

Maaseh Breishis is different. It is allowed to be taught to a single disciple no matter who they are. This is because all of Maaseh Breishis is related to the physical world and is practical to a certain degree. However, it is not allowed to be taught to a group in case some people in the group try to interpret the subject matter themselves. It is a difficult subject and it lends itself to misinterpretation. If people learned it in a group then they will come to misunderstand the subject and believe in improper ideas.

These are the reasons why Maaseh Breishis can be taught to anyone, but Maaseh Merkavah must be withheld from the general public. Maaseh Merkavah, even with a proper teacher is so abstract and difficult that not just anyone can learn it. A person who learns this subject, when they are unprepared, is likely to have many problems with the ideas contained within it. However, Maaseh Breishis can be taught to anyone with the proper teacher.