We describe the approach taken by the nineteenth-century Cambridge textbook author J. M. F. Wright to a notoriously difficult part of Newton’s Principia: the method of first and last ratios. Wright suggested an algebraic point of view that, to his mind, would not only remove all prior confusion over the method, but would also serve as a new foundation for calculus as a whole. We examine the details of Wright’s approach, and discuss whether it was as successful as he claimed it to be.