His work, as a great originator, in my opinion, was done. The two books now before the world [i.e., A System of Logic and Principles] were the main constructions that his accumulated stores had prepared him for; and I do not think that there lay in him the materials of a third at all approaching to these. It is very unlikely indeed that he was even physically capable of renewing the strain of the two winters 1842–1843 and 1846–1847. His subsequent years were marked by diminished labours on the whole; while the direction of these labours was towards application, exposition and polemic, rather than origination; and he was more and more absorbed in the outlook for social improvements.The years on which this book focuses seem to be the most productive period in Mill’s intellectual life, when he fully developed his own view on man and society, which differed from what he saw as the Benthamite one in certain crucial aspects. Besides its significance in its own right, his intellectual activity at this period is of huge importance for the further understanding of his later major works that appeared in the 1850s onwards, for these works were the projects to which he deployed all the ideas he had developed by the mid-1840s.