  According to Lyon and Colyvan, a proper account of explanations in science requires an analysis of mathematical explanations in pure mathematics.  Indeed, this was also the major intuition behind Steiner’s account of mathematical explanation in science offered in 1978b, whose central idea was that a mathematical explanation of a physical fact is one in which a mathematical explanation of a mathematical fact results when we remove the physics. Steiner used as central example for his analysis Euler’s theorem on the existence of an instantaneous axis of rotation in rigid body kinematics. Baker 2009a discusses briefly Steiner’s account and declares it ‘seriously flawed’(p. 623) but Molinini 2012 is more enlightening as it subjects the Euler example used by Steiner to a detailed scrutiny and compares alternative explanatory proofs of the same result. Steiner’s theory, as we have mentioned, requires an account of mathematical explanations of mathematical facts, which he provided in Steiner 1978a. It is important to add that serious objections have been raised to the idea that mathematical explanations of scientific facts require a mathematical explanation of a mathematical fact as part of the explanation. For instance, Baker 2015 argues against Steiner’s account by pointing out that in the cicada case or in the honeycomb cell case only the mathematical results are appealed to but not their proofs.