Long before this search for proportion reached business, it manifested itself in art. Once again, the human body is the quintessential paradigm of this search. But an art as mathematical as music has also pointed, since the 13th century, in another direction. The Huelgas codex is a great example of these new searches for forms of harmony. With the appearance of polyphony (a cantus mensurabilis) we are shown again the idea that reason and measurement can give new systems of balance, discarding the old ideals. 

The proportion, since thE Middle Ages, began to detach itself from an absolute value and linked to memory (such as Gregorian chant, or Romanesque architecture) to also become a field of experimentation of reason.