John Stuart Mill (1806–1873) was born in London, son of the Scottish historian of India and philosopher, James Mill, by whom he was educated in, among other things, the principles of British empiricism and Benthamite utilitarianism. Like his father, he worked for the East India Company, being in charge of the Company's relations with the native states 1836–1856, and head of the examiner's office from 1856 until the powers of the Company were transferred in 1858. The book which established Mill as a philosopher was his System of Logic (1843), described in its full title as ‘a connected view of the principles of evidence and the methods of scientific investigation’. Book 6 of the System of Logic was ‘On the logic of the moral sciences’, and at the end of it Mill declared, without trying to justify it, his opinion that there is a ‘general principle to which all rules of practice ought to conform’; namely that of ‘conduciveness to the happiness of mankind, or rather, of all sentient beings’. For example, we should keep our promises not because we can see intuitively the truth of the precept, but because it passes the utilitarian test. Mill's justification for this opinion was in his Utilitarianism (1863). Mill's version of utilitarianism differed from Bentham's in that he recognized not only quantitative but also qualitative differences between pleasures.