Let us, then, refer to a few types certain of instant recognition. The most notable of modern instances is Dr. Oliver Wendell Holmes, a specialist in his profession, a hard-working physician, and the author of valuable treatises on medical art, who nevertheless occupied the position of being among the four chief poets whom America has produced, and one of the most versatile of the litterateurs of the century. He went to the Paris Medical Schools shortly after he had graduated at Harvard; he practised as a physician at Boston; and for nearly forty years he was Professor of Physiology. Yet he had time to write the most delightful and original of philosophical essays, to publish novels of which at least one--"Elsie Venner: A Romance of Destiny"--will rank as a classic; to deliver orations and after-dinner speeches in sparkling verse, and to write exquisite poems in rich and felicitous language on a wonderful variety of themes, the complete collection of which makes a very substantial volume. In all his work Dr. Holmes showed himself to be the profound student of nature and of humanity with many varying interests; yet we can often trace the hand of the physician in the work of the essayist and poet. His novels were special studies which only the ardent physiologist and metaphysician would have cared to discuss, or, at all events, would have discussed so well. Both "Elsie Venner" and "The Guardian Angel" deal with the occult problems of heredity, and those problems are treated with the power of the specialist in certain branches of science. Still more strongly is the character of the medical man displayed in a number of the poems, some by reason of their subject, and some by the figures and imagery they contain. The well-known "Stethoscope Song" will immediately suggest itself in illustration. But, for purposes of quotation, I prefer a less popular poem of rare beauty, which more strikingly manifests the writer's power of transmuting the hard dry facts of science into light and gleaming poetry. I refer to what he called at first "The Anatomist's Hymn," but afterwards "The Living Temple." It is one of the interpolated poems in the "Autocrat" series of papers, and to my thinking invests the human body and its physical functions with unimagined charms. Take, for instance, this poetic exposition of our respiration, the scientific correctness and exactness of which need no explanation to readers of this volume:-- "The smooth, soft air with pulse-like waves Flows murmuring through its hidden caves, Whose streams of brightening purple rush Fired with a new and livelier blush, While all their burden of decay The ebbing current steals away, And red with Nature's flame they start From the warm fountains of the heart.