Certainly the fact is sufficiently well established that there are and have been different philosophies. The Truth is, however, one; and the instinct of reason maintains this irradicable intuition or belief. It is said that only one philosophy can be true, and, because philosophies are different, it is concluded that all others must be erroneous. But, in fact, each one in turn gives every assurance, evidence and proof of being the one and true Philosophy. This is a common mode of reasoning and is what seems in truth to be the view of sober thought. As regards the sober nature of the word at issue—thought—we can tell from every-day experience that if we fast we feel hunger either at once or very soon. But sober thought always has the fortunate power of not resulting in hunger and desire, but of being and remaining as it is, content. Hence the thought expressed in such an utterance reveals the fact that it is dead understanding; for it is only death which fasts and yet rests satisfied. But neither physical life nor intellectual remains content with mere abstention; as desire it presses on through hunger and through thirst towards Truth, towards knowledge itself. It presses on to satisfy this desire and does not allow itself to feast and find sufficiency in a reflection such as this. As to this reflection, the next thing to be said of it is that however different the philosophies have been, they had a common bond in that they were Philosophy. Thus whoever may have studied or become acquainted with a philosophy, of whatever kind, provided only that it is such, has thereby become acquainted with Philosophy. That delusive mode of reasoning which regards diversity alone, and from doubt of or aversion to the particular form in which a Universal finds its actuality, will not grasp or even allow this universal nature, I have elsewhere[4] likened to an invalid recommended by the doctor to eat fruit, and who has cherries, plums or grapes, before him, but who pedantically refuses to take anything because no part of what is offered him is fruit, some of it being cherries, and the rest plums or grapes. But it is really important to have a deeper insight into the bearings of this diversity in the systems of Philosophy. Truth and Philosophy known philosophically, make such diversity appear in another light from that of abstract opposition between Truth and Error. The explanation of how this comes about will reveal to us the significance of the whole history of Philosophy. We must make the fact conceivable, that the diversity and number of philosophies not only does not prejudice Philosophy itself, that is to say the possibility of a philosophy, but that such diversity is, and has been, absolutely necessary to the existence of a science of Philosophy and that it is essential to it.