First Period.—This commences at the time of Thales, about 600 B.C., and goes on to the coming to maturity of the Neo-platonic philosophy with Plotinus in the third century; from thence to its further progress and development with Proclus in the fifth century until the time when all philosophy was extinguished. The Neo-platonic philosophy then made its entrance into Christianity later on, and many philosophies within Christianity have this philosophy as their only groundwork. This is a space of time extending to about 1000 years, the end of which coincides with the migration of the nations and the decline of the Roman Empire.
Second Period.—The second period is that of the Middle Ages. The Scholastics are included in it, and Arabians and Jews are also historically to be noticed, but this philosophy mainly falls within the Christian Church. This period is of something over 1000 years’ duration.
Third Period.—The Philosophy of modern times made its first independent appearance after the Thirty Years’ War, with Bacon, Jacob Böhm and Descartes; it begins with the distinction contained in: cogito ergo sum. This period is one of a couple of centuries and the philosophy is consequently still somewhat modern.
[2. Sources of the History of Philosophy.]
We have to seek for sources of another kind in this than in political history. There historians are the fountainheads, which again have as sources the deeds and sayings of individuals; and the historians who are not original have over and above performed their work at secondhand. But historians always have the deeds already present in history, that is to say, here brought into the form of ordinary conception; for the name of history has two meanings: it signifies on the one hand the deeds and events themselves, and on the other, it denotes them in so far as they are formed through conception for conception. In the history of Philosophy there are, on the contrary, not any sources which can be derived from historians, but the deeds themselves lie before us, and these—the philosophic operations themselves—are the true sources. If we wish to study the history of Philosophy in earnest, we must go to such springs as these. Yet these operations form too wide a field to permit of our keeping to it alone in this history. In the case of many philosophers it is absolutely necessary to confine oneself to the original authors, but in many periods, in which we cannot obtain original sources, seeing that they have not been preserved to us, (as, for instance, in that of the older Greek philosophy) we must certainly confine our attention simply to historians and other writers. There are other periods, too, where it is desirable that others should have read the works of the philosophers and that we should receive abstracts therefrom. Several schoolmen have left behind them works of sixteen, twenty-four and twenty-six folios, and hence we must in their case confine ourselves to the researches of others. Many philosophic works are also rare and hence difficult to obtain. Many philosophers are for the most part important from an historic or literary point of view only, and hence we may limit ourselves to the compilations in which they are dealt with. The most noteworthy works on the history of Philosophy are, however, the following, regarding which I refer for particulars to the summary of Tennemann’s History of Philosophy, by A. Wendt, since I do not wish to give any complete list.
1. One of the first Histories of Philosophy, which is only interesting as an attempt, is the “History of Philosophy,” by Thomas Stanley (London, 1655, folio ed. III., 1701, 4. translated into Latin by Godofr. Olearius, Lipsiæ, 1711, 4). This history is no longer much used, and only contains the old philosophic schools in the form of sects and as if no new ones had existed. That is to say, it keeps to the old belief commonly held at that time, that there only were ancient philosophies and that the period of philosophy came to an end with Christianity, as if Philosophy were something belonging to heathendom and the truth only could be found in Christianity. In it a distinction was drawn between Truth as it is created from the natural reason in the ancient philosophies, and the revealed truth of the Christian religion, in which there was consequently no longer any Philosophy. In the time of the Revival of Learning there certainly were no proper philosophies, and above all in Stanley’s time systems of Philosophy proper were too young for the older generations to have the amount of respect for them necessary to allow of their being esteemed as realities.
2. Jo. Jac. Bruckeri Historia critica philosophiæ, Lipsiæ, 1742-1744, four parts, or five volumes in four, for the fourth part has two volumes. The second edition, unaltered, but with the addition of a supplement, 1766-1767, four parts in six quartos, the last of which forms the supplement. This is an immense compilation which is not formed straight from the original sources, but is mixed with reflections after the manner of the times. As we have seen from an example above (p. 43) the accounts given are in the highest degree inaccurate. Brucker’s manner of procedure is entirely unhistoric, and yet nowhere ought we to proceed in a more historic manner than in the history of Philosophy. This work is thus simply so much useless ballast. An epitome of the same is Jo. Jac. Bruckeri Institutiones historiæ philosophicæ, usui academicæ juventutis adornatæ, Lipsiæ, 1747, 8; second edition, Leipzig, 1756; third edition prepared by Born, Leipzig, 1790, 8.
3. Dietrich Tiedmann’s Geist der Speculativen Philosophie, Marburg, 1791-1797, 6 vols., 8. He treats of political history diffusely, but without any life, and the language is stiff and affected. The whole work is a melancholy example of how a learned professor can occupy his whole life with the study of speculative philosophy, and yet have no idea at all of speculation. His argumenta to the Plato of Brucker are of the same description. In every history he makes abstracts from the philosophers so long as they keep to mere ratiocination, but when the speculative is arrived at, he becomes irate, declaring it all to be composed of empty subtleties, and stops short with the words “we know better.” His merit is that he has supplied valuable abstracts from rare books belonging to the Middle Ages and from cabalistic and mystical works of that time.
4. Joh. Gottlieb Buhle: Lehrbuch der Geschichte der Philosophie und einer kritischen Literatur derselben, Göttingen, 1796 to 1804, eight parts, 8. Ancient philosophy is treated with disproportionate brevity; the further Buhle went on, the more particular he became. He has many good summaries of rare works, as for instance those of Giordano Bruno, which were in the Göttingen Library.
5. Wilh. Gottl. Tennemann’s Geschichte der Philosophie, Leipzig, 1798—1819, eleven parts, 8. The eighth part, the Scholastic Philosophy, occupies two volumes. The philosophies are fully described, and the more modern times are better done than the ancient. The philosophies of recent times are easier to describe, since it is only necessary to make an abstract or to interpret straight on, for the thoughts contained in them lie nearer to ours. It is otherwise with the ancient philosophers, because they stand in another stage of the Notion, and on this account they are likewise more difficult to grasp. That is to say, what is old is easily overthrown by something else more familiar to us, and where Tennemann comes across such he is almost useless. In Aristotle, for instance, the misinterpretation is so great, that Tennemann foists upon him what is directly opposite to his beliefs, and thus from the adoption of the opposite to what Tennemann asserts to be Aristotle’s opinion, a correct idea of Aristotelian philosophy is arrived at. Tennemann is then candid enough to place the reference to Aristotle underneath the text, so that the original and the interpretation often contradict one another. Tennemann thinks that it is really the case that the historian should have no philosophy, and he glories in that; yet he really has a system and he is a critical philosopher. He praises philosophers, their work and their genius, and yet the end of the lay is that all of them will be pronounced to be wanting in that they have one defect, which is not to be Kantian philosophers and not yet to have sought the source of knowledge. From this the result is that the Truth could not be known.