Mill is one of the most intensely studied nineteenth-century political thinkers. Partly thanks to the publication of his Collected works by Toronto University Press, his philosophical thought, personal and public life, political career and rhetorical style have been minutely studied and dissected by scholars of the calibre of Alan Ryan, Gertrude Himmelfarb and Stefan Collini. Could there be anything new and revealing to write about him? Yet, Timothy Larsen has produced what must rank as one of the briefest and by far the most original and exciting of the intellectual biographies of this Victorian giant. Mill was hitherto known as the champion of Utilitarianism and ‘the saint of rationalism’ – a perception initiated by Mill himself in his autobiography and sustained by generations of scholars over the centuries. Through a careful and detailed analysis of an impressive range of sources, Larsen reveals the full extent of Mill's immersion in, and engagement with, Christian theology and biblical culture, which also shaped both his parents and his sisters. Despite his repeated proclamations of religious indifference, Mill was close to men and women from just about every denominational background within the Christian tradition. His writings were widely admired by both Nonconformists and Churchmen. On liberty – which has sometimes been regarded as an ‘attack’ on organised Christianity – was welcomed and praised by the Evangelical press. Later, his Examination of Sir William Hamilton's philosophy (1865), in which Mill rejected the notion that God's morality is so much superior to ours that we need to accept it even when its dictates are apparently unethical, far from being perceived as the ultimate statement of humanist autonomy, was endorsed by clergymen and Christian writers ranging from Nonconformist divines to Roman Catholic theologians (p. 193). Again, as in Liberty, Mill presented his case in ‘secular’ terms, but his mindset was so deeply inspired by Christian values that what he wrote came across as more truly ‘Christian’ than some of the elaborations of the theologians whom he attacked. Perhaps the most arresting part of Larsen's analysis is his exploration of Helen Taylor's spiritual trajectory. Helen Taylor was the only daughter of Mill's wife, Helen, and was very close to Mill himself, especially in his last years. Usually regarded as a purely secular utilitarian liberal-socialist and a feminist, Larsen reveals her to have been a convert to Roman Catholicism, or at least a fellow--traveller, for most of her life. Part of his evidence comes from Helen's diary, which she kept from the early 1840s and which scholars had until now largely ignored. So, from beginning to end, Mill's ‘secular’ life was in fact very ‘spiritual’. The case that Larsen puts forward is compelling and must force scholars to a reassessment of the Victorian liberal philosopher's whole ‘system’, particularly in the sphere of politics, ethics and logic.