Why is that the first abstraction? I would think at least one of these three earlier developments would be: 1) deductive geometry of Thales, where we could now

Why is that the first abstraction? I would think at least one of these three earlier developments would be: 1) deductive geometry of Thales, where we could now prove things independent of the physical world (abstracting away from the physical) 2) Plato’s remarks on incommensurability (proto irrational numbers) being something real but not physical, because no physical process could prove to the mathematician that two lengths really have no common unit measure. Here the abstraction is again away from physical means. 3) infinity of numbers. Abstracting away from large but finite collections. We can only ever survey finite collections physically, again is an abstraction.