Rambam-Maaseh Merkava (Subject Title for discussing G-D's Existence)- Yisodei Hatorah perek 2 halacha 11

The Rambam wants to define the subject matter that he has been discussing for the first two chapters of Yisodei Hatorah. He says,


דברים אלו שאמרנו בענין זה בשני פרקים אלו כמו טיפה מן הים הם ממה שצריך לבאר בענין זה. וביאור כל העיקרים שבשני פרקים אלו הוא הנקרא מעשה מרכבה:


"These things that we have said regarding the matters in these first two chapters is like a drop in the ocean of what must be explained about these matters. The explanation of all of these fundamental ideas in these first two chapters is referred to as Maaseh Merkava."

Now that the Rambam has brought up the phrase "Maaseh Merkava" it is important to understand what that means. According to Rambam the "maaseh Merkava" refers to Metaphysics. Basically, the understanding of G-D. The words refer to the vision of Ezekial that he saw a chariot (Merkava) that G-D was on being led by four Chayos, the highest level of angels.

The Rambam is simply pointing out that he is not giving a detailed description of the "Maaseh Merkava," rather he is just teaching the foundations that one needs in order to understand it on a basic level. This is is why the Rambam devotes a small section to these ideas in the Mishna Torah. However, in his famous work The Guide for the Perplexed, the Rambam discusses the "Maaseh Merkava" in great detail.