Mathematical modelling is a group of techniques which have been making their way into diverse biological fields. The incipient roles of these techniques in biology are transforming the scientific practice, and it is believed that the mathematization of biology is progressively putting it in line with the standards of rigor of the physical sciences. While the first statement is true, the second does not necessarily follow from it. In this paper, I will challenge the idea that mathematics brings biology closer to the standards of physics by showing how teleological notions, common in biology but not in today's physics, coexist and interact with modelling techniques in a very idiosyncratic scientific practice. To this end, I will explore modelling techniques of the so-called brain's internal compass, a component of the "brain GPS system," in computational neuroscience.