The Birthday of John Venn (1834) — Visualising Logic

John Venn introduced the overlapping circles that bear his name in his 1881 book ‘Symbolic Logic’. Venn diagrams provided a simple, intuitive way to represent sets and their intersections, unions, and complements. They became a standard tool for teaching logic, probability, and database theory. Venn was also a priest and built a machine for bowling cricket balls. The diagrams were not original to him — Euler and Leibniz used similar ideas — but Venn systematised them and made them accessible to generations of students.