This Flemish botanist came to Leiden in 1593 and turned a herb garden into the famous Hortus Botanicus. Clusius studied medicine and botany. Before he came to Leiden, he was botanist at Emperor Maximilian II’s court in Vienna. A new hortus was laid out in Leiden under his supervision in 1594, with a large inventory of plants consisting of 1584 items. Clusius also introduced the tulip into Europe. His research formed the foundation for the Dutch bulb-growing industry. The current Clusius garden is a reconstruction of the very first Hortus Botanicus.

Boerhaave was a doctor, professor, and Rector Magnificus at Leiden University. He unleashed a revolution in the medical world: he focused first and foremost on the patient. In 1714, this Leiden professor introduced classes taught at patients’ sickbeds. He transformed the art of medicine from theoretical into practical, with a focus on research. This resulted in the academic hospital: the Caecilia Guesthouse on the Lange St. Agnietenstraat. This building is currently the home of the Boerhaave Museum.

Thorbecke was professor of Diplomacy and Modern History, a member of the Dutch Lower House, a minister and founder of parliamentary democracy. His publications formed the foundation for a revision of the Constitution in 1848. This new constitution brought about direct elections and ministerial responsibility. Thorbecke led three cabinets and is known as one of the most influential statesmen of Dutch history.

Thanks to German physician Von Siebold, Leiden was able to evolve into an expert centre on Asian history and culture. He was also very important for botanical culture; in the 1820s Von Siebold lived in Japan and when he returned to Europe, he brought over 730 plant species with him. Some of those original plants can still be found in the Hortus Botanicus. His former home on the Rapenburg is now home to Japan Museum Sieboldhuis.

Professor Experimental Physics, Nobel Prize Winner and founder of the Leiden Instruments Makers School. Kamerlingh Onnes became renowned for his research on liquefying helium in his low-temperature laboratory..  He converted helium into liquid form and discovered that metals become superconductive at very low temperatures.  In 1913, he received a Nobel Prize for his research.

Historian, cultural philosopher, anthropologist and founder of modern Dutch cultural history and history of mentalities. In 1915, Huizinga became Professor of General History at Leiden University. In the 1920s, he received worldwide fame for his book The Autumn of the Middle Ages. He was nominated for the Nobel Prize for Literature several times. He was also honorary supervisor for Princess Juliana of the Netherlands when she was made an honorary doctor.

One of the most well-known and important physicists in history, Albert Einstein is especially known for his theories of relativity. He had a close relationship with Leiden. He once applied to Heike Kamerlingh Onnes for a job and in 1912, Hendrik Lorentz asked him to be his successor, an invitation that Einstein declined. In 1920, Einstein was appointed professor by special appointment by his good friend Paul Ehrenfest (Lorentz’ successor). Einstein taught several guest lectures a year at Leiden University.

Professor of Law and member of the Council of State, Cleveringa is best known for his 1940 speech in which he denounced the German occupying forces for dismissing his Jewish colleagues Meijers and David. Cleveringa was arrested and his protest led to a strike and to the closing of the university. The Cleveringa lecture and Cleveringa chair commemorate his brave action.