Hence, in the latest decades of the century, there has come a revival of interest in philosophy, and especially in the idealistic philosophy of its first years. But if philosophy has revived, it is in a more critical and cautious form, and accompanied by a clear consciousness that the only true idealism is that which is able to absorb and assimilate all the data supplied by empirical investigation, and do justice to all the results of the special sciences. The general movement of thought in the nineteenth century has thus, on the whole, taken an idealistic direction; but there has come with it also a deeper consciousness of the immense difficulty of a comprehensive synthesis; of the inefficacy of any easy monism or optimism, that would pluck the fruit of knowledge before it is ripe; of the infinite labor and patience, the sympathetic appreciation of the opposing views of others, and constant and unsparing criticism of our own, which are needed for the construction of a true philosophy. II In a short article like this, it is impossible to give more than a few indications of the way in which this three-fold _schema_ of the history of nineteenth-century philosophy should be filled up. To give any definite impression, the writer must, so to speak, put on the seven-leagued boots of Jack the Giant Killer; in other words, however conscious he may be of the truth that _dolus latet in generalibus_, he must generalize and be content to mention only a few leading names in illustration of the tendencies of thought of which he speaks.