"This notion leads to universal necessity and fate, by supposing that motives have the same relation to the will of an intelligent agent, as weights have to a balance; so that of two things absolutely indifferent, and intelligent agent can no more choose either, than a balance can move itself when the weights on both sides are equal."
A Collection of Papers, Which Passed Between the Late Learned Mr. Leibnitz, and Dr. Clarke, In the Years 1715 and 1716
<u>A Collection of Papers, Which Passed Between the Late Learned Mr. Leibnitz, and Dr. Clarke, In the Years 1715 and 1716: Relating to the Principles of Natural Philosophy and Religion. With an appendix. To which are added, Letters to Dr. Clarke concerning Liberty and Necessity; from a Gentleman of the University of Cambridge: with the Doctor's Answers to Them. Also Remarks upon a book, Entituled, A Philosophical Enquiry Concerning Human Liberty</u> (London: James Knapton, 1717). &lt;<a href="http://books.google.com/books?id=_RUHAAAAQAAJ">Link to Google Books</a>&gt;<br>
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See also <u>The Leibniz-Clarke Correspondence: Together wiith Extracts from Newton's Principia and Opticks</u>. Ed. H.G. Alexander (Manchester: Manchester UP, 1998).