Question: Who first classified the fundamental elements as earth, air, fire, and water?

Answer: The Greek philosopher Empedocles in the 5th century BC. This particular diagram reflects Aristotle's classification.

In ancient times, the Chinese proclaimed the five basic components (Pinyin WU XING) of the physical universe to be: earth, wood, metal, fire, and water.

In India, in the Samkhya-karikas by Ishvarakrsna (c. 3rd century AD), the five gross elements are: space, air, fire, water, and earth.