 During the last third of the 20th-century, fibre bundles and their Lie groups have virtually taken over fundamental physics. This is not the place to explain how or why, but the unstoppable evolution of physics towards ever more mathematically sophisticated, prima facie less straightforward representations of its subject-matter, deserves the attention of philosophers. It is clear that the concept of a definite stable thing out there, which might, at least in principle, be held and manipulated, is no longer so serviceable to us as it was once to our flint-carving ancestors. 