I find the notion of structure of currently debated Epistemic Structural Realism (ESR) ambiguous. I show that the disambiguation leads to two views of structure ESR₁ and ESR₂. Only ESR₂ can be seen as asserting that structure is a set of relevant relations usually captured in physics by equations. I indicate that such view needs an argument in principle to explain why structure is epistemically prior. I show that Ramsey Sentences play a role in establishing such an argument and identify the ultimate argument in the thesis of Kantian Humility.