The magic bullet is a scientific concept developed by the German Nobel laureate Paul Ehrlich in 1907. While working at the Institute of Experimental Therapy (Institut für experimentelle Therapie), Ehrlich formed an idea that it could be possible to kill specific microbes (such as bacteria), which cause diseases in the body, without harming the body itself. He named the hypothetical agent as Zauberkugel, and used the English translation "magic bullet" in The Harben Lectures at London. The name itself is a reference to an old German myth about a bullet that cannot miss its target. Ehrlich had in mind Carl Maria von Webers popular 1821 opera Der Freischütz', in which a young hunter is required to hit an impossible target in order to marry his bride.
Ehrlich envisioned that just like a bullet fired from a gun to hit a specific target, there could be a way to specifically target invading microbes. His continued research to discover the magic bullet resulted in further knowledge of the functions of the body's immune system, and in the development of Salvarsan, the first effective drug for syphilis, in 1909. His works were the foundation of immunology, and for his contributions he shared the 1908 Nobel Prize in Physiology or Medicine with Élie Metchnikoff.
Ehrlich's discovery of Salvarsan in 1909 for the treatment of syphilis is termed as the first magic bullet. This led to the foundation of the concept of chemotherapy.