Certain trees depend for the spread of their kind on seeds equipped with spiral wings that when they fall they may reach the ground outside the shadow of the parent tree and so have a chance to grow into wide-spreading trees. Thomas Lincoln, the father of Abraham, was as the spirals that carried the precious seed where it could have free air and an unshadowed soil to grow in. And there the tuition of the experiences that made all men kin and so made a natural democracy possible began. He had little teaching of the formal sort. Six months or a year in a log schoolhouse probably measured its duration. He had the sterner discipline of the fields, the waters, and the trees, for their very temptations became disciplines to those who resisted, as his father did not. He learned his parables of the fields and of the natural instincts of his neighbors. He knew both physical and human nature about him, and this he illustrated, expressed, in such manner as to make him a faithful and favorite exponent of its coarseness, its kindliness, its gallantry, its sympathies, and its heroisms. These neighborly fellowships, not affected but genuine, equipped him not only with a vital and never-failing sense of brotherhood but with a faith in those whom he called the "plain people," the common man. His creed was, if not innate, innurtured. That fellowship and that faith were at the bottom of his democracy--not merely patient love of his neighbors but faith in their ultimate judgments--democracy that made him a nationalist and a world humanist. But in the making of Lincoln there were more than the usual disciplines. He had also the tuition of the "solemn solitude," as Bancroft says. He sought the fellowships of the past--of that "invisible multitude of the spirits of yesterday." He read every book that he could get within fifty miles, it is said. But what is more certain is that he read thoroughly and "inwardly digested" a few books. He knew the Bible, Shakespeare, and Burns, Aesop's "Fables," Bunyan's "Pilgrim's Progress," and "Robinson Crusoe." He read a history of the United States and a life of Washington, and he learned by heart the statutes of the State of Indiana. Moreover, he studied without guidance algebra and geometry. It is said that later in life, when his political career was beginning, he continued his studies even more seriously and attempted to master a foreign language.