Paul Ehrlich was a German physician and scientist born in 1854, known for his pioneering work in immunology and chemotherapy. He is best recognized for developing the first effective treatment for syphilis, called Salvarsan, which marked a significant advancement in medical science. Ehrlich's research laid the groundwork for the field of pharmacology and earned him the Nobel Prize in Physiology or Medicine in 1908. In addition to his contributions to medicine, Ehrlich was a prominent advocate for the use of dyes in biological research, which led to the development of staining techniques that are still used today. His work in serology helped to advance the understanding of the immune system and its response to pathogens.