this, and combination of the data given in it: accordingly he can convince. He ought therefore to beware of falling into the way of the mystics, and, for example, by the assertion of intellectual intuitions or pretended immediate apprehensions of the reason, to seek to make a vain show of positive knowledge of that which is for ever inaccessible to all knowledge, or at the most can be indicated by means of a negation. The value and worth of philosophy lies in the fact that it rejects all assumptions which cannot be established, and takes as its data only what can be certainly proved in the world given in external perception, in the forms of apprehension of this world, which are constitutive of our intellect, and in the consciousness of one's own self which is common to all. Therefore it must remain cosmology, and cannot become theology. Its theme must limit itself to the world; to express in all aspects what this is, what it is in its inmost nature, is all that it can honestly achieve. Now it answers to this that my system when it reaches its highest point assumes a negative character, thus ends with a negation. It can here speak only of what is denied, given up: but what is thereby won, what is laid hold of, it is obliged (at the conclusion of the fourth book) to denote as nothing, and can only add the consolation that it is merely a relative, not an absolute nothing. For if something is none of all the things which we know, it is certainly for us, speaking generally, nothing. But it does not yet follow from this that it is absolutely nothing, that from every possible point of view and in every possible sense it must be nothing, but only that we are limited to a completely negative knowledge of it, which may very well lie in the limitation of our point of view. Now it is just here that the mystic proceeds positively, and therefore it is just from this point that nothing but mysticism remains. However, any one who wishes this kind of supplement to the negative knowledge to which alone philosophy can guide him will find it in its most beautiful and richest form
