Golden Mean or Fibonacci series. The number of clockwise and counterclockwise spirals in a sunflower are always two consecutive Fibonacci numbers.

le mona lisa. genius

Darth Vader, Mona Lisa, and The Golden Mean :: Margins of error

Da Vinci's Vitruvian Man

“The primary factor is proportions. Proportions are what makes the old Greek temples classic in their beauty. They are like huge blocks, from which the air has been literally hewn out between the columns.