LYELL'S COPY OF THE FIRST VOLUME OF HIS FOUNDATIONAL WORK OF MODERN SCIENCE, THE MOST IMPORTANT GEOLOGICAL BOOK OF THE NINETEENTH CENTURY. Lyell demonstrated that large-scale changes in the Earth's physical geography could be explained by uniform geological causes observable in the present day, rather than by catastrophic or biblical events. The implications of Lyell's study would have a profound effect on the development of evolutionary theory. Lyell's "influence on Darwin was incalculable. When the Beagle expedition sailed in 1831 Henslow presented Darwin with the first volume of Lyell's Principles of Geology ... with the strong injunction that he should 'on no account accept the views therein advocated.' The second volume of Lyell's book (see following two lots) reached Darwin in Montevideo and his constant reference to the enormous influence on this thinking of this great work are typified by a letter from him to Leonard Horner saying 'I always feel as if my books came half out of Lyell's brain.' Both Haeckel and Huxley regarded the Origin a necessary corollary to Lyell's Principles. Darwin, indeed, was intent upon carrying Lyell's demonstration of the uniformity of natural causes over into the organic world" (PMM 344)