The Golden Ratio or Golden Section, which is known since ancient times, is the division ratio of a distance or other size, where the ratio of the whole to its larger part is equal to the ratio of the larger to the smaller part.

Pictures and objects that are constructed according to the proportions of the Golden Section are said to have a special aesthetic effect.

If one divides a square following the law of the Golden Section and connects the corner points with a curved line, the rotation creates a logarithmic or «golden» spiral. Such a logarithmic spiral, for example, underlies the construction of the shell of a living fossil, the Nautilus (a relative of the squids), whereby it becomes clear that logarithmic spirals play an important role in biological growth processes (compare the figure above).

The shell of the extinct ammonoids, relatives of the squids from the time of the dinosaurs, had the same construction principle. Also here we find the logarithmic spiral of high harmony realised (see below).