It is evident, however, that as the work progressed, the interest of the various questions bearing on the origin of species grew in his mind. While Lyell found it impossible to accept the explanation of origin suggested by Lamarck, he was greatly influenced by the arguments in favour of evolution advanced by that naturalist; and as he wrote chapter after chapter on the questions of the modification and variability of species, on hybridity, on the modes of distribution of plants and animals, and their consequent geographical relations, and discussed the struggle of existence going on everywhere in the organic world, in its bearings on the question of 'centres of creation,' he found the second volume growing altogether beyond reasonable limits. His intense interest in this part of his work is shown by his remark, 'If I have succeeded so well with inanimate matter, surely I shall make a lively thing when I have chiefly to talk of living beings[58]?'
By December 1831, Lyell had come to the resolution to publish the chapters of his work which dealt with the changes going on in the organic world as a volume by itself. This second volume of the Principles he gracefully dedicated to his friend Broderip, who had rendered him such valuable assistance in all questions connected with Natural History.
This volume appeared in January 1832, at the same time that a second edition of the first volume was also issued. The reception of the second volume by the public appears to have been not less favourable than that of the first.
In March 1831, Lyell had accepted the Professorship of Geology in King's College, London. In addition to his desire to aid in the work of scientific education, in which he had always taken so great an interest, Lyell seems to have felt that the task of presenting his views in a popular form would be aided by his having to expound them to a miscellaneous audience. For two years, these lectures were delivered, and attracted much attention; the favourable impressions produced by them on a man of the world have been recorded by Abraham Hayward, and on more scientific thinkers by Harriet Martineau.
The third volume of the Principles was not completed till a second edition of the second volume had been issued. This third volume, appearing in May 1833, dealt with the classification of the Tertiary strata, to which Lyell had devoted so much labour, studying conchology under Deshayes, and visiting all the chief Tertiary deposits of Europe for the collection of materials. The application of the principles enunciated in the two earlier volumes to the unravelling of the past history of the globe, constituted the chief task undertaken in this part of the great work. But not a few controversial questions were dealt with, and the famous 'metamorphic theory' was advanced in opposition to the Wernerian hypothesis of 'primitive formations.' The volume was appropriately dedicated to Murchison, who had been Lyell's companion in the famous Auvergne excursion, which had produced such an effect on his mind.
Within a twelvemonth, a third edition of the whole work in four small volumes was issued, and in the end no less than twelve editions of the Principles of Geology were issued, in addition to portions separately published under the titles of Manual, Elements, and Student's Elements of Geology, of all of which a number of editions have appeared. Lyell was always the most painstaking and conscientious of authors. He declared 'I must write what will be read[59],' and he spared no labour in securing accuracy of statement combined with elegance of diction. His father, a good classical and Italian scholar, had done much towards assisting him to attain literary excellence, and at Oxford, where he took a good degree in classics, he was greatly impressed by the style of Gibbon's writings, and practised both prose and poetic compositions with great diligence.
Both Darwin and Huxley always maintained that the real charm and power of Lyell's work are only to be found in the first edition[60]. As new discoveries were made or more effective illustrations of his views presented themselves to his mind, passage after passage in the work was modified by the author or replaced by others; and the effects of these constant changes—however necessary and desirable in themselves—could not fail to be detrimental to the book as a work of art. He who would form a just idea of the greatness of Lyell's masterpiece, must read the first edition, of course bearing in mind, all the while, the state of science at the time it was written.