 The philosopher George Berkeley (1685–1753), noted both for his subjective idealist doctrine of esse est percipi and his denial of general ideas, was a persistent critic of the presuppositions underlying the mathematical practice of his day (Jesseph 1993). His most celebrated broadsides were directed at the calculus, but in fact his conflict with the mathematicians went deeper. For his denial of the existence of abstract ideas of any kind went in direct opposition with the abstractionist account of mathematical concepts held by the majority of mathematicians and philosophers of the day. The central tenet of this doctrine, which goes back to Aristotle, is that the mind creates mathematical concepts by abstraction, that is, by the mental suppression of extraneous features of perceived objects so as to focus on properties singled out for attention. Berkeley rejected this, asserting that mathematics as a science is ultimately concerned with objects of sense, its admitted generality stemming from the capacity of percepts to serve as signs for all percepts of a similar form.