First documented in 300 BC by Greek mathematician Euclid, the Fibonacci sequence is a mathematical formula that suggests that each number is equal to the sum of the two numbers that precede it.

Initially thought to be exclusive to mathematics, this became a formula with a ratio that appears in very specific elements in nature; plants, seed growth, and the human ear, and may be considered a universal formula.

The rule of thirds speaks directly to a simplified version of the golden ratio where a similar approach to producing an aesthetically pleasing image is possible.

Luca Pacioli wrote a book called De Divina Proportione (1509), which detailed the collaborative insights and findings of the application of the golden ratio in various disciplines.

The positioning of the Mona Lisa’s head, neckline, garment, and arm indicate some use of the golden ratio. Although unclear, it can still be said that the breadth of her face could be very close to the golden ratio of the canvas width.