Such a study would also furnish valuable data for determining precisely the variation of form which alteration of conditions causes in the development of such a struggle. In the East, the history of religion, for which material is supplied by the study of the Zend and Sanskrit literature, (3) would furnish examples of attempts made by philosophers to find a rational solution of the problems of the universe, and to adjust the theories of speculative thought to the national creed deposited in supposed sacred books. And though, in a western nation such as Greece, the separation of religion from philosophy was too wide to admit of much parallel in the speculative aspect of free thought, yet in reference to the critical, many instances of the application of an analogous process to a national creed may be seen in the examination made of the early mythology, the attempt to rationalize it by searching for historical data in it, or to moralize it by allegory.(66) Again, within the sphere of the Hebrew religion which, though supernaturally suggested, developed in connexion with human events so as to admit the possibility of the rise of mental difficulties in the progress of its history, how much hallowed truth, both theoretical and practical, might be learned from the divine breathings of pious inquirers, such as the sacred authors of the seventy-third Psalm, or of the books of Job and Ecclesiastes, which give expression to painful doubts about Providence, not fully solved by religion, but which nevertheless faith was willing to leave unexplained.(67) If in the Oriental systems free thought is seen to operate on a national creed by adjusting it to new ideas through philosophical dogmatism; if in the Greek by explaining it away through scepticism; in the Hebrew it is hushed by the holier logic of the feelings. The two former illustrate steps in the intellectual progress of free thought; the last exhibits the moral lesson of resignation and submission in the soul of the inquirer.