This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Isaac Newton worked out the essentials of the derivative in private notes dating to the mid-1660s and did not publish them for decades. Gottfried Leibniz, working independently in Germany, published his own version, with the dy/dx notation still in use today, in 1684, and for a while nobody on the continent had reason to think Newton had gotten there first. When the Royal Society, of which Newton was president, formally investigated the question of priority in 1712, it found in Newton's favor, which surprises nobody once you notice who was doing the investigating. Historians today generally accept that both men reached the calculus independently, working from different starting intuitions (Newton's from physics and motion, Leibniz's from a more purely symbolic, algebraic approach) and that the accusations of plagiarism thrown by both sides' supporters, which poisoned relations between British and continental mathematics for most of the eighteenth century, were unfounded. The practical cost was real: British mathematicians, loyal to Newton's notation out of national pride, fell behind their continental counterparts, who adopted Leibniz's more flexible dy/dx system and used it to develop calculus faster. The dispute is exactly the kind of priority argument the atlas records as a dissent rather than settling by fiat; crediting one side alone is a convention, not a finding.