The monograph outlines the dual role of mathematics in relation to beauty. On one hand mathematics refers to an objective, through mathematical formulas expressible side of beauty. On the other hand, it points out that entirely abstract things like mathematical equations can be seen as beautiful, too. This refers to two aspects of beauty. 1. The biological, evolutionary: The monograph outlines the dual role of mathematics in relation to beauty. On the one hand our brains react to certain aesthetic stimuli in scientifically adequately explainable way. 2. Philosophical-spiritual: This shows a connection of beauty with goodness and being. To such a perception we can mature. As a hint can be mentioned handed down wisdom: You cannot find beauty, if you don´t carry it in yourself. Such an analysis can help us understand why we use the word beauty in so many different ways.