Top 3 Math ematicians 1 Leonhard Euler Leonhard Euler was an 18th century physicist and scholar who was responsible for developing many concepts that are an integral part of modern mathematics. Revolutionary Principles Over his career, Euler came up with an array of principles which laid the foundation for much of modern mathematics as we know it. He was a revolutionary thinker in the fields of geometry, trigonometry, calculus, differential equations, number theory and notational systems—including the utilization of π and f(x) —among a legion of other accomplishments. His Euler's Identity theorem is often cited as the most delightful of equations and his work also focused on the fields of astronomy/lunar motion, acoustics, mechanics and music. Euler was a highly prolific author, having written hundreds of papers and publications over his lifetime, including the well-known science and philosophy series Letters to a German Pri