Book excerpt: In the New Essays on Human Understanding, Leibniz argues chapter by chapter with John Locke's Essay Concerning Human Understanding, challenging his views about knowledge, personal identity, God, morality, mind and matter, nature versus nurture, logic and language, and a host of other topics. The work is a series of sharp, deep discussions by one great philosopher of the work of another. Leibniz's references to his contemporaries and his discussions of the ideas and institutions of the age make this a fascinating and valuable document in the history of ideas. The work was originally written in French, and the version by Peter Remnant and Jonathan Bennett, based on the only reliable French edition (published in 1962), first appeared in 1981 and has become the standard English translation. It has been thoroughly revised for this series and provided with a new and longer introduction, a chronology on Leibniz's life and career and a guide to further reading.