Such a boy was Sir William Hooker, the subject of this lecture. He was born in 1785, at Norwich. There is no detailed history of his boyhood, but it is known that in his school days he interested himself in entomology, in drawing, and in reading books of natural history, a rather unusual thing at the time of the Napoleonic wars! In 1805, when he was at the age of 20, he discovered a species new to Britain, in _Buxbaumia aphylla_, and his correspondence about it with Dawson Turner shows that he was already well versed not only in the flowering plants, but also in the Mosses, Hepaticae, Lichens, and fresh-water Algae of Norfolk, his native county. Three years later Sir James Smith dedicated to him the new genus _Hookeria_, styling him as "a most assiduous and intelligent botanist, already well known by his interesting discovery of _Buxbaumia aphylla_, as well as by his scientific drawings of Fuci for Mr Turner's work: and likely to be far more distinguished by his illustrations of the difficult genus _Jungermannia_, to which he has given particular attention" (_Trans. Linn. Soc._ IX. 275). Clearly young Hooker was a convinced naturalist in his early years, and that by inner impulse rather than by the mere force of circumstances. [Illustration: _Plate XII_ WILLIAM JACKSON HOOKER (1834)] Not that the circumstances of his early years were in any way against his scientific tastes. He inherited a competence at the early age of four, and so was saved the mere struggle of bread-winning. His father was personally interested in gardening, while from his mother's side he inherited a taste for drawing. Moreover, he was early thrown into relations with some of the leading naturalists of his time, chiefly it appears by his own initiative, and doubtless he owed much in those opening years to the advice and stimulus of such men as Dawson Turner, and Sir James Smith. Elected to the Linnean Society in 1806, he became acquainted in the same year with Sir Joseph Banks, Robert Brown, and other leading naturalists. Thus when other young men would be feeling for their first footing, he at the age of 21 had already penetrated into the innermost circle of the Science of the country. For a period of sixty years he held there a place unique in its activity. He shared with Augustin Pyrame De Candolle and with Robert Brown the position of greatest prominence among systematists, during the time which Sachs has described as that of "the Development of the Natural System under the Dogma of Constancy of Species." The interval between the death of Linnaeus and the publication of the _Origin of Species_ can show no greater triumvirate of botanists than these, working each in his own way, but simultaneously.