When was the scientist that  revealed by means of microscopy the previously unknown world of microorganisms born?
Antonie van Leeuwenhoek Antonie Philips van Leeuwenhoek ( , ] ; 24 October 1632 – 26 August 1723) was a Dutch businessman, scientist, and one of the notable representatives of the Golden Age of Dutch science and technology. A largely self-taught man in science, he is commonly known as "the Father of Microbiology", and often considered to be the first acknowledged microscopist and microbiologist. Van Leeuwenhoek is best known for his pioneering work in the field of microscopy and for his contributions toward the establishment of microbiology as a scientific discipline.
Peter Medawar Sir Peter Brian Medawar {'1': ", '2': ", '3': ", '4': "} ( ; 28 February 1915 – 2 October 1987) was a British biologist born in Brazil, whose work on graft rejection and the discovery of acquired immune tolerance was fundamental to the practice of tissue and organ transplants. For his works in immunology he is regarded as the "father of transplantation". He is remembered for his wit in real life and popular writings. Famous zoologists such as Richard Dawkins, referred to him as "the wittiest of all scientific writers", and Stephen Jay Gould, as "the cleverest man I have ever known".