 Bradley’s most sustained treatment of logic comes in The Principles of Logic, published contemporaneously with Frege’s Grundlagen. The benefit of hindsight provides a striking contrast between these works, the former apparently looking back to the nineteenth century, the latter anticipating the twentieth. While both books eschew formal methods, in Frege’s case this results merely from an attempt to give a readable account of some applications of mathematical logic. But the absence of formulae (theorems, axioms, rules of inference) from Bradley’s book is intrinsic to it, expressing an opposition (shared by Mill) to the formalization of reasoning in principle, as detaching inference from the practical acquisition of scientific knowledge. This, together with the fact that familiar terms (e.g. ‘contradiction’) are used in unfamiliar ways, gives the book an archaic feel. Nevertheless, and despite the fact that Principles would no longer ordinarily be consulted by a modern logician unless for historical purposes, it focuses on issues central to logic, and the impression of its being backward-looking is to some extent misleading: for example, it uses the older vocabulary of ‘ideas’ and ‘judgments’ to express views which, often through their (selective) impact upon Russell, gave rise to doctrines subsequently expressed in terms of sentences and propositions; and it effectively exposed the notions of meaning and reference to a sceptical scrutiny which has continued long since.