The Golden Ratio (ϕ) is a mathematical constant approximately equal to 1.618, often called the "divine proportion."
It appears in nature, from the spirals of sunflower seeds to the structure of galaxies, and has been used in art and architecture, including the Parthenon and Da Vinci's "Vitruvian Man." ✍️
Bernhard Riemann (1826–1866) was famously introverted and originally intended to study theology. Only after receiving encouragement (and financial backing) did he switch his focus to mathematics. His 1854 habilitation lecture on geometry—attended by Gauss—introduced the revolutionary idea of what we now call “manifolds,” steering geometry into new, higher-dimensional domains.