Anaximander was born in 611 BC. After Thales died, he continued his position as principal at Miletus. In addition, he also wrote papers on geometry. He put more emphasis on research on the ball and developing philosophical ideas related to space and time.

He was the first to introduce the use of a gnomon, a stick that was mounted on a level ground to calculate time. Furthermore, this technique is used as the basis for the creation of sun disc (sundial) to determine the calculation of time. His work in the world of mathematics was to pioneer the study of the ball and its success in making the globe. He also succeeded in bridging mathematical thinking, from Thales to Phytagoras.

Meanwhile, Anaximander states that apeiron (something that has no limits) is the logos of the universe. However, he did not explain the meaning of the word “unlimited”. Perhaps, this statement can be imagined as an object without unlimited and unlimited quality.

The existence of this apeiron is supported by several arguments, namely the infinite is a source, the source is infinite, and something is not water or air, because the two substances are opposites (if opposed, the two substances destroy each other).

This Apeiron also has an important role for the creation of the cosmos (universe). The eternal movement is the source of the origin of the sky. Therefore, Anaximander began to form a picture of the universe. He drew the model in round shapes that represented the earth, planets and stars. He described a planet behind another planet based on geometry and mathematics, not just mythology.

He claimed that the sun and stars were fires trapped in cold air. These objects appear not directly, but through channels like a trumpet. In addition, he also believes that the earth is cylindrical and has no buffer. According to him, the body of the sky orbits the earth.

He often makes “courageous” research, such as questioning the truth of the myths of the gods. Because he wanted to explain natural phenomena rationally, he stated that lightning was not caused by Zeus, but by pneuma or compressed air. He died in 545 BC.