Template:Selected anniversaries/June 21
1652: Architect Inigo Jones dies. He was one of the first architects of the early modern period to employ Vitruvian rules of proportion and symmetry in his buildings.
1781: Mathematician and physicist Siméon Denis Poisson born. His memoirs on the theory of electricity and magnetism will constitute a new branch of mathematical physics.
1947: Lorenz system diagram develops self-awareness, invents new class of Gnomon algorithm functions which detect and prevent crimes against mathematical constants.
1948: Biologist, mathematician, and classics scholar D'Arcy Wentworth Thompson dies.
1952: Crime-fighter The Governess chastises corrupt accounting firm, compels accountants to return money embezzled from orphan's fund and personally apologize to orphans.