Eighteen hours of labor daily, and yet he was happy! He had found his life-work now. To a sister he writes about the beetles at Aix. He cannot be laughed out of this study as when a boy. He has been to Parma, to see Professor Guidotti's "finest collection of fossil-shells in Italy, ... spending three days, from six o'clock in the morning till night, exchanging our respective commodities." To his sisters he writes all his discoveries in rocks and fossils, with the enthusiasm of a boy. "I rode to the upper Val d'Arno,--a famous day for me,--an old lacustrine deposit, corresponding delightfully with our Angus lakes in all but age and _species_ of animals; same genera of shells. They have just extracted the fortieth skeleton of hippopotamus; have got about twenty elephants, one or two mastodons, a rhinoceros and stags, and oxen out of number.... At Rome I found the geology of the city itself exceedingly interesting. The celebrated seven hills, of which you have read, and which in fact are nine, are caused by the Tiber and some tributaries, which have cut open valleys almost entirely through volcanic ejected matter, covered by travertine containing lacustrine shells." He made the ascent of Etna, and sketched the crater. "Inside the crater, near the lip, were huge masses of ice, between which and the scoriæ and lava of the crater issued hot sulphurous vapors, which I breathed in copiously; and for six hours after I could not, even after eating and drinking, get the horrid taste out of my mouth, for my lungs had got full of it. The wind was so high, that the guide held my hat while I drew; but though the head was cold, my feet got so hot in the cinders, that I was often alarmed that my boots would be burnt." In 1830, the first volume of "Principles of Geology, being an Attempt to Explain the Former Changes of the Earth's Surface by Reference to Causes now in Operation," was published. "It will not pretend," he wrote to Murchison, "to give even an abstract of all that is known in geology, but it will endeavor to establish the _principles_ of _reasoning_ in the science; and all my geology will come in as illustration of my views of those principles, and as evidence strengthening the system necessarily arising out of the admission of such principles, which, as you know, are neither more nor less than that _no causes whatever_ have from the earliest time to which we can look back, to the present, ever acted, but those _now acting_.... I must go to Germany.... Their language must be learnt; the places to which their memoirs relate, visited; and then you may see, as I may, to what extent we may indulge dreams of eminence, at least as original observers." He, too, like all the other great ones, indulged in "dreams of eminence." Did ever man or woman achieve anything worthy without these dreams?