September 21

Born in 1501 in Pavia, Cardano earned his medical doctorate at the University of Padua in 1525. His 1545 publication 'Ars Magna' introduced solutions to cubic and quartic equations, marking a milestone in algebra. Cardano's interest in games of chance led him to explore probability theory decades before it was formalized. As a physician, he served patients across Italy and wrote on diverse medical topics, some of which were controversial. His work as an astrologer included casting horoscopes for notable figures of his time. Cardano's vibrant personality and personal trials, including legal troubles, did little to diminish his lasting impact on mathematics, medicine, and the occult.

Born in 1647, Acker pursued studies in theology and history at universities in Germany before launching his academic career. He served as a professor of history and rhetoric at the University of Jena, delivering lectures on ecclesiastical events and Reformation history. Acker published detailed chronicles of German principalities, drawing on extensive archival research. His humanist training and rigorous methodology influenced the development of modern historiography. Beyond his writings, he engaged in theological debates, contributing to intellectual discourse of his era. Acker’s works offered one of the earliest systematic accounts of 16th-century church affairs. He died in 1719, leaving behind a significant body of historical scholarship.

Born in 1688, Jai Singh II ascended the throne of Amber at age eleven and later transformed it into the planned city of Jaipur in 1727. He undertook military campaigns to defend his state from Mughal and Maratha pressures and maintained diplomatic ties with Delhi. A passionate scholar of astronomy and mathematics, he constructed five observatories across India for precise celestial measurements. His most famous observatory in Jaipur features massive stone instruments that are now a UNESCO World Heritage site. Jai Singh published astronomical tables and corresponded with European scholars, bridging cultural divides. He implemented administrative reforms and urban planning that shaped Jaipur’s unique grid layout. He died in 1743, celebrated for blending scientific achievement with enlightened governance.

Born in 1798 in Sainte-Foy-la-Grande, Beaumont studied geology and engineering, eventually becoming a professor at the École des Mines in Paris. He is best known for developing the geosyncline theory, explaining how Earth's crust folds and uplifts to form mountain ranges. His fieldwork across the Alps and Pyrenees provided detailed maps and insights into structural geology. Beaumont also contributed to engineering projects, advising on mining and canal construction throughout France. His systematic approach to geological survey helped professionalize the discipline before his death in 1874.

Born in 1809 in Petorca, Chile, Montt pursued legal and philosophical studies in Santiago and Europe before entering public service. As Minister of the Interior, he championed education and infrastructure, founding universities and improving roads. Elected president in 1851, he served two terms during which he strengthened central authority and promoted economic growth through mining and agriculture. His administration faced political unrest and a civil war in 1859, which he quelled while expanding civil liberties. Montt's emphasis on secular education and administrative efficiency laid foundations for Chile's modernization before his passing in 1880.

Léon Charles Thévenin was born in 1857 in Meaux, France, and graduated from the École Polytechnique. He joined the French Post and Telegraph service, where he conducted groundbreaking research on electrical networks. In 1883, he published what became known as Thevenin’s theorem, demonstrating that any linear electrical network can be reduced to a single voltage source and resistance. His work laid the foundation for modern circuit theory and remains a cornerstone of electrical engineering education. Thévenin eventually rose to the rank of Inspector General of Telegraphs before retiring, leaving a legacy that endures in textbooks and engineering practice.

Josef Müller was a Croatian entomologist born in 1880. He conducted extensive research on the taxonomy and biology of various insect groups. Müller published numerous scientific papers describing new species and genera. He played a key role in developing entomological collections at regional museums. His work helped advance the understanding of insect diversity in southeastern Europe. He died in 1964, leaving foundational contributions to the field of entomology.

Bernardo Houssay was born in 1887 in Buenos Aires and became a leading physiologist. He researched the role of pituitary hormones in regulating blood sugar. In 1947, he was awarded the Nobel Prize in Physiology or Medicine for these discoveries. Houssay founded research institutes in Argentina, fostering scientific education and culture. He mentored generations of Latin American scientists and advocated for research funding. Houssay's contributions laid the groundwork for modern endocrinology. He passed away in 1971, honored as Argentina's first Nobel laureate in the sciences.

Benjamin Graham (1894-1976) was a British-American economist and professor hailed as the father of value investing. He co-authored 'Security Analysis' (1934), laying the groundwork for fundamental stock evaluation. As a professor at Columbia Business School, Graham mentored students like Warren Buffett, imparting his disciplined investment philosophy. His later book, 'The Intelligent Investor' (1949), remains a classic guide for investors worldwide. Graham emphasized the 'margin of safety' concept and advocated for investment over speculation. He founded several investment partnerships that achieved consistent long-term returns. Graham's analytical approach transformed Wall Street practices and academic research. His enduring influence is evident in countless investment strategies and the success of his disciples.

Orlando Letelier (1932-1976) was a Chilean economist, diplomat, and politician who held key posts under President Salvador Allende. As Minister of Foreign Affairs, he promoted progressive economic policies and international alliances. Following the 1973 coup, Letelier was exiled and became a vocal opponent of Augusto Pinochet's dictatorship. He directed the Institute for Policy Studies in Washington, conducting research on human rights and Chilean affairs. On September 21, 1976, Letelier was assassinated by a car bomb in Washington, D.C., in an act orchestrated by Chilean intelligence. His death galvanized global condemnation of the Pinochet regime and underscored transnational repression. Letelier's legacy endures in the struggle for democracy and human rights in Latin America.

Born in 1954 in Jaffna, Sri Lanka, Rajini Thiranagama earned her medical degree before joining the University of Jaffna faculty. As an academic, she specialized in anatomy and lecture-based research but grew increasingly concerned by violence engulfing her homeland. She co-founded the University Teachers for Human Rights, gathering testimonials on civilian atrocities committed by all sides. Thiranagama published critical reports exposing violations during the Sri Lankan civil war, risking her safety to defend truth. Her outspoken activism made her a target, and she was tragically assassinated in 1989. Her writings continue to serve as vital testimonies in the struggle for justice and reconciliation in Sri Lanka.

Born in 1934, Leonid Rogozov was selected as the sole doctor for the 1960–1961 Soviet Antarctic expedition at Novolazarevskaya Station. When he developed acute appendicitis far from medical facilities, he undertook the unprecedented task of operating on himself. Assisted by a handful of untrained colleagues, he completed the surgery successfully under local anesthesia. His remarkable self-surgery made international headlines and remains a unique example of medical resilience. Rogozov later returned to Leningrad where he continued his surgical career and trained future doctors. He passed away in 2000, leaving a legacy of courage and ingenuity.