Analytic geometry, both in the sense of Fermat and Descartes, and in the modern sense of "Feynman diagrams" encrypting algebraic axioms. Certainly the former precedes Wallis, Newton, and Leibniz, and from a modern perspective, it seems trivial, too trivial to mention. But that geometric problems can be dealt with analytically (algebraically), and vice versa, helped formulate and inform the revolutions of science.

I agree that we have not yet understood the role that algebraic diagrammatics play in our understanding of mathematics, physics, or even how they will affect the average person in the street. However, I will be surprised if they are not at least as important as the use of arrows to indicate functions. (They are a generalization thereof).