"J. J. C. Smart, a prominent 20th-century utilitarian, said simply that [Sidgwick's] The Methods is ‘the best book ever written on ethics’. Derek Parfit agreed with that judgement, acknowledging that some books, like Plato’s Republic and Aristotle’s Ethics, are greater achievements, but noting that because Sidgwick could build on the work of his predecessors, The Methods ‘contains the largest number of true and important claims’."