Rambam- All Things Under the Heavens- Yisodei Hatorah perek 4 halacha 1

In this section of the Rambam, he discusses the makeup of all things on Earth. He says,


ארבעה גופים הללו שהם אש ורוח ומים וארץ הם יסודות כל הנבראים למטה מן הרקיע. וכל שיהיה מאדם ומבהמה ועוף ורמש ודג וצמח ומתכת ואבנים טובות ומרגליות ושאר אבני בנין והרים וגושי עפר הכל גולמן מחובר מארבעה יסודות הללו. נמצאו כל הגופים שלמטה מן הרקיע חוץ מארבעה יסודות האלו מחוברים מגולם וצורה. וגולם שלהם מחובר מארבעה יסודות האלו. אבל כל אחד מארבעה היסודות אינו מחובר אלא מגולם וצורה בלבד:


"These four elements- fire, wind, water and earth - are the foundations of all the creations under the heavens. All things like Man, animals, birds, bugs, fish, plants, metals, precious stones, pearls, building materials, mountains, clods of earth, everything physical, is bound from these four elements. It is found that all bodies under the heavens, except for these four elements, consist of a combined form and shape and their shape consists of the four elements, but each of the four elements consists of just a combined shape and form."

In The Guide for the Perplexed (Section 1 Chapter 58) the Rambam uses the idea of the four elements to describe an understanding of G-D. He says,

"I would observe that, -- as has already been shown -God's existence is absolute, that it includes no composition, as will be proved, and that we comprehend only the fact that He exists, not His essence. Consequently it is a false assumption to hold that He has any positive attribute: for He does not possess existence in addition to His essence: it therefore cannot
be said that the one may be described as an attribute [of the other]; much less has He [in addition to His existence] a compound essence, consisting of two constituent elements to which the attribute could refer: still less has He accidents, which could be described by an attribute. Hence it is clear that He has no positive attribute whatever. The negative attributes, however, are those which are necessary to direct the mind to the truths which we must believe concerning God; for, on the one hand, they do not imply any plurality, and, on the other, they convey to man the highest possible knowledge of God; e.g., it has been established by proof that some being must exist besides those things which can be perceived by the senses, or apprehended by the mind; when we say of this being, that it exists, we mean that its non-existence is impossible. We then perceive that such a being is not, for instance, like the four elements, which are inanimate, and we therefore say that it is living, expressing thereby that it is not dead."

The four elements can be contrasted to G-D in the sense that G-D can be understood when compared to the four elements. These four elements make up all physical beings and the only way that we, according to the Rambam, can understand G-D is through what He is not. With this in mind, an understanding of all physical material is essential if we are to truly understand G-D.