In the middle of the eighteenth century, anyone who wanted to learn calculus had a problem. Newton and Leibniz’s invention was only seventy years old, and its results were scattered across papers in scientific journals, letters and books written in Latin, French and English, in different notations. The only famous textbook, the Marquis de L’Hôpital’s Analysis of the Infinitely Small, of 1696, dealt only with differential calculus. There was no book that led the student, step by step, from algebra to differential equations.