Already Harvey's mind was quite made up as to what line in life he would prefer. He cannot hope, he says, to achieve success in commerce, by "buying cheap and selling dear." As regards professions, he is "neither fit to be a doctor nor a lawyer, lacking courage for the one, and face for the other, and application for both.... All I have a taste for is natural history, and that might possibly lead in days to come to a genus called _Harveya_, and the letters F.L.S. after my name, and with that I shall be content.... The utmost extent of my ambition would be to get a professorship of natural history."
His parents had thought of placing the boy with an eminent chemist in London, but his obvious antipathy to the prospect of city life led to his entering his father's office in Limerick instead. The quiet home life which ensued was well suited to his taste. All holidays were devoted to collecting. The family had a summer residence at Miltown Malbay, on the Atlantic coast, an excellent spot for Algae; and it was no doubt the time spent there that brought these plants prominently under his notice, and led to the noteworthy researches of later days. For the time, Mollusca still mainly occupied his mind, and in 1829, at eighteen years of age, we find him busily engaged in drawing the plates for a _Testacea Hibernica_--a book that never saw the light, though two years later he writes of being at work on his _Bivalvia Hibernica_, which was then half finished.
In the same year, he made his first excursion into "foreign parts" as he calls them, visiting Dublin, Liverpool, London, Edinburgh and Glasgow. An account of a meeting of the Linnean Society, to which he was taken by his friend Bicheno, then secretary, and at which "if not edified I was amused," shows that the reverence he felt for science did not necessarily extend to constituted scientific authority. "The President wore a three-cocked hat of ample dimensions, and sat in a crimson arm-chair in great state. I saw a number of new Fellows admitted. They were marched one by one to the president, who rose, and taking them by the hand, admitted them. The process costs _£_25."
In 1831, his finding at Killarney of the beautiful moss _Hookeria laetevirens_, hitherto unknown in Ireland, led to the formation of one of the warmest and most valuable friendships of his life. He forwarded specimens, with a characteristic letter, to W. J. Hooker at Glasgow, and the kind and encouraging reply which he received led to further letters and eventually to an intimacy which seems to have been prized equally on both sides. Hooker recognized at once the extraordinary talent of the shy young man of twenty, lent him books, asked him to visit him, and congratulated him on his critical faculty, predicting for him a rapid advance to "the top of algologists." Another life-long friendship made about this time was with Mrs Griffiths of Torquay; and he numbered Greville and Agardh among his earliest correspondents. Already he was deep in his life-task of comparing and describing plants, working with the restless energy which characterised him. "I rise at five every morning," he writes, "and work till breakfast, examining or describing the Algae for the 'British Flora[109].' If I do five species a day I think it good work. This may seem slow, but there is much to be compared and _corrected_! for I differ from Dr Hooker on many species. Oh, impudence! oh, presumption!" In 1832 he undertook to do the Algae for J. T. Mackay's _Flora Hibernica_, which was published three years later; this was his most important contribution to the botany of his native land.