The period of magic extended from prehistoric times to about the beginning of the 1st century AD. Most people believed that natural processes were controlled by spirits, and they relied on magic to persuade the spirits to help while they conducted practical operations. Very little progress was made toward understanding how the universe is made, but much practical knowledge was gathered. Perhaps 9,000 years ago, people devised reliable techniques for making and sustaining fire. Gradually they learned to use fire to harden pottery, extract metals from ores, make alloys, and develop materials such as glass. Certain elements that occur naturally in a pure state, such as gold, copper, and sulfur, were recognized and valued for their properties. This was the period of the Sumerian, Babylonian, Egyptian, and Greek cultures.
About 400 BC the Greek philosopher Democritus theorized that all matter was made up of tiny, indivisible units he called atoms, but his idea was not based on scientific evidence. Other Greek philosophers, including Thales and Aristotle, also speculated on the nature of matter, though their theories, too, had little in common with modern chemical knowledge. They believed that earth, air, fire, and water (some imagined a fifth substance called “quintessence”) were the basic elements of all matter. They speculated on the possibility of removing such qualities as hardness, heat or cold, and color from common materials and combining them to make rarer or more valuable substances. They knew that iron could be drawn from a dirty, brown earthen rock and that bronze was made by combining copper and tin. Therefore it seemed possible that if yellowness, hardness, and other qualities could be properly combined, the product would be gold. Such speculations gave rise to alchemy.