Alchemy is an early protoscientific and philosophical discipline combining elements of chemistry, metallurgy, physics, medicine, astrology, semiotics, mysticism, spiritualism, and art. Alchemy has been practiced in ancient Egypt, India, and China, in Classical Greece and Rome, in the Islamic empire, and then in Europe up to the 19th century — in a complex network of schools and philosophical systems spanning at least 2500 years.
Western alchemy has always been closely connected with Hermeticism, a philosophical and spiritual system that traces its roots to Hermes Trismegistus, a syncretic Egyptian-Greek deity and legendary alchemist. These two disciplines influenced the birth of Rosicrucianism, an important esoteric movement of the 17th century. In the 19th century, as mainstream alchemy evolved into modern chemistry, its mystic and Hermetic aspects became the focus of a modern spiritual alchemy, where material manipulations are viewed as mere symbols of spiritual transformations.
The alchemists did not follow what is now known as the scientific method, and much of the "knowledge" they produced was later found to be banal, limited, wrong, or meaningless. Today, the discipline is of interest mainly to historians of science and philosophy, and for its mystic, esoteric, and artistic aspects. Nevertheless, alchemy was one of the main precursors of modern sciences, and we owe to the ancient alchemists the discovery of many substances and processes that are the mainstay of modern chemical and metallurgical industries.