Scientific knowledge has often been reproached for being one-sided, for unjustly preferring one particular kind of knowledge and proudly but blindly neglecting other kinds which are just as good and even more profound. We have convinced ourselves, I think, that these reproaches are utterly unfounded, and the result of grave misunderstandings. The main cause of these misunderstandings is the erroneous opinion that knowledge could be anything but formal, that in some way or other it must be possible to grasp and express content. We know this to be nonsense, and therefore impossible for the language of every day life, art, religion just as well as for science. So science is not inferior to anything else in this respect; on the contrary, it avails itself to the fullest extent of all the possibilities of the one kind of knowledge which is the only kind. Life and art are centered around "enjoyment" of content, for them expression is not the ultimate end, but only a means, and is, accordingly, valued only in so far as it leads to the production (not communication) of certain contents.
Expression itself is incomparably less perfect in all other fields than in science, and science has never pretended to replace art or life.
It is often said that science in its most perfect form, as mathematical physics, takes into account the quantitative aspects of experience only, and neglects altogether its qualitative sides. We recognise in this complaint a form of the same confusion and prejudice against which we had to fight all the time: "quality" may be regarded as the popular word for Content. (I have avoided the use of the word quality in this sense, because the word may stand, and often does stand, for properties which are not Content at all, according to our way of speaking.) This charge against science has no more justification than all the others. The quantitative method, characterised by the use of numbers in the representation of logical structure, is for practical as well as theoretical reasons, the very best instrument of knowledge, and science should be praised for using it as much as possible. The theoretical reasons, if I may just hint at them, lie in the fact that counting and numbering is made possible by the repeated occurence of similar or equal events in experience; and, as we stated at the beginning, it is exactly this repetition of similarity in the world, which forms the basis of all possible knowledge. There are no "quantitative aspects" in the world, besides these similarities; the adjective "quantitative" can be applied to the method only, not to
