And he goes on to tell us that their influence always remained with him. Their human, their important, their comprehensive ideas, grasping the whole of life in one image, together with their clear, natural, and transparent mode of expression, adapted precisely to their thoughts, seemed to him to be in the greatest contrast with the writings of moderns, without definiteness or order in expression, and without vitality or purpose in thought,--"written as if for another world." Thus Leibniz learned two of the great lessons of his life,--to seek always for clearness of diction and for pertinence and purpose of ideas. Historians and poets first occupied him; but when in his school-life, a lad of twelve or thirteen years, he came to the study of logic, he was greatly struck, he says, by the "ordering and analysis of thoughts which he found there." He gave himself up to making tables of categories and predicaments, analyzing each book that he read into suitable topics, and arranging these into classes and sub-classes. We can imagine the astonishment of his playmates as he burst upon them with a demand to classify this or that idea, to find its appropriate predicament. Thus he was led naturally to the philosophic books in his father's library,--to Plato and to Aristotle, to the Scholastics. Suarez, in particular, among the latter, he read; and traces of his influences are to be found in the formulation of his own philosophic system. At about this same time he took great delight in the theological works with which his father's library abounded, reading with equal ease and pleasure the writings of the Lutherans and of the Reformed Church, of the Jesuits and the Jansenists, of the Thomists and the Arminians. The result was, he tells us, that he was strengthened in the Lutheran faith of his family, but, as we may easily imagine from his after life, made tolerant of all forms of faith. In 1661 the boy Leibniz, fifteen years old, entered the University of Leipzig. If we glance back upon his attainments, we find him thoroughly at home in Latin, having made good progress in Greek, acquainted with the historians and poets of antiquity, acquainted with the contemporary range of science, except in mathematics and physics, deeply read and interested in ancient and scholastic philosophy and in the current theological discussions. Of himself he says:-- "Two things were of extraordinary aid to me: in the first place, I was self-taught; and in the second, as soon as I entered upon any science I sought for something new, even though I did not as yet thoroughly understand the old. I thus gained two things: I did not fill my mind with things empty and to be unlearned afterwards,--things resting upon the assertion of the teacher, and not upon reason; and secondly, I never rested till I got down to the very roots of the science and reached its principles."