The connection between science and mathematics is often considered necessary and insoluble. Therefore, a relationship between mathematics and humanities or arts is deemed exceptional or sometimes unnatural. Nevertheless, on the basis of historical, ontological and epistemological researches it can be noted that it’s impossible to warrant the immediate identification between mathematics and sciences on a deeper level than the practical one. Given the instrumentality and then the unnecessity of this connection, the relationship between mathematics and not-scientific disciplines is undeniable, even if the mathematics in the explicit formalisms which we know doesn’t appear in them. It’s possible to demonstrate this relationship not only with philosophical argumentations, but also whit empirical verifications, e.g. in the music and in particular in the music of J. S. Bach. Such an epistemological thought finally leads to the question on the possibility of knowledge in the art in comparison to the epistemological characteristics of the Galilean and Post-Galilean science.