But it is not remarkable that, with all his realistic tendencies, Comenius did not consistently employ induction. The natural sciences were young in his day, so that he did not altogether grasp their content and method, and he had partially inherited the scholastic notion that truth cannot be fully secured through the senses or by reason. It is sufficient merit that Comenius, for the first time in history, applied anything like induction to teaching. Moreover, in the application of his general method to the specific teaching of various lines,--sciences, reading, writing, singing, languages, morality, and piety, he utilized more fully the induction of Bacon. For example, after showing the necessity for careful observation in obtaining a knowledge of the sciences, he gives nine useful precepts for their study that are clearly the inductive result of his own experience as a teacher. Likewise, he insists that, in teaching the sciences, in order to make a genuine impression upon the mind, one must deal with realities rather than books. The objects themselves, or where this is not possible, such representations of them as can be conveyed by copies, models, and pictures, must be studied. After the same principle he formulates inductive rules and methods for instruction in the other subjects. [Sidenote: Popularity of his Latin text-books,] [Sidenote: but ignorance of the _Great Didactic_,] [Sidenote: which was the indirect basis of modern education.] =The Influence of Comenius upon Education.=--Thus the work of Comenius was based primarily upon sense realism, but he added many modifications and new elements of his own. He may in the fullest sense be considered the great educational theorist and practical reformer of the seventeenth century. His practical ability is especially shown in the series of Latin text-books, which far excelled the works of several contemporaries on similar lines. The _Janua_ was translated into a dozen European, and at least three Asiatic languages; the _Orbis Pictus_ proved even more popular, and went through an almost unlimited number of editions in various tongues; and the whole series became for many generations the favorite means of introducing young people to the study of Latin. But the remarkable theoretical work of Comenius had little effect upon the schools of the period, and until about the middle of the nineteenth century the _Great Didactic_ was scarcely known. At that time, when this treatise of Comenius was brought to light by German investigators, it was discovered that the old realist of the seventeenth century had been the first to deal with education in a scientific spirit, and work out its problems practically in the schools. And the principles of Comenius were at the time unconsciously taken up by others and indirectly became the basis of modern education. His spirit appeared not only in the ideas of subsequent theorists--Francke, Rousseau, Basedow, Pestalozzi, Herbart,