" Robins realized more clearly than did Jurin the nature of the limit concept. He recognized that the phrase "the ultimate ratio of vanishing quantities" was a figurative expression, referring , not to a last ratio, but to a "fixed quantity which some varying quantity, by a continual augmentation of diminuation shall perpetually approach,... provided the varying quantity can be made in its approach to the other to differ from it by less than by and quantity how minute soever, that can be assigned, .."though it can never be made absolutely equal to it. "

― , The History of the Calculus and Its Conceptual Development