In the winter of 1836 Emerson followed up his discourse on Nature by a course of twelve lectures on the "Philosophy of History," a considerable portion of which eventually became embodied in his essays. The next year (1837) was the year of the delivery of the _Man Thinking, or the American Scholar_ address before the Phi Beta Kappa Society at Cambridge. This society, composed of the first twenty-five men in each class graduating from college, has annual meetings which have called forth the best efforts of many distinguished scholars and thinkers. Emerson's address was listened to with the most profound interest. It declared a sort of intellectual independence for America. Henceforth we were to be emancipated from clogging foreign influences, and a national literature was to expand under the fostering care of the Republic. These two discourses, _Nature_ and _The American Scholar_, strike the keynote of Emerson's philosophical, poetical, and moral teachings. In fact he had, as every great teacher has, only a limited number of principles and theories to teach. These principles of life can all be enumerated in twenty words--self-reliance, culture, intellectual and moral independence, the divinity of nature and man, the necessity of labor, and high ideals. Emerson spent the latter part of his life in lecturing and in literary work. His son, Dr. Edward Emerson, gave an interesting account of how these lectures were constructed. "All through his life he kept a journal. This book, he said, was his 'Savings Bank.' The thoughts thus received and garnered in his journals were indexed, and a great many of them appeared in his published works. They were religiously set down just as they came, in no order except chronological, but later they were grouped, enlarged or pruned, illustrated, worked into a lecture or discourse, and, after having in this capacity undergone repeated testing and rearranging, were finally carefully sifted and more rigidly pruned, and were printed as essays." Besides his essays and lectures Emerson left some poetry in which is embodied those thoughts which were to him too deep for prose expression. Oliver Wendell Holmes in speaking of this says: "Emerson wrote occasionally in verse from his school-days until he had reached the age which used to be known as the grand climacteric, sixty-three.... His poems are not and hardly can become popular; they are not meant to be liked by the many, but to be dearly loved and cherished by the few.... His occasional lawlessness in technical construction, his somewhat fantastic expressions, his enigmatic obscurities hardly detract from the pleasant surprise his verses so often bring with them.... The poetic license which we allow in the verse of Emerson is more than excused by the noble spirit which makes us forget its occasional blemishes, sometimes to be pleased with them as characteristic of the writer."