nature itself; science does not "pick out" the quantitative sides of things, and it does not think of overlooking qualities as if they did not exist.
The semblance as if scientists simply disregarded qualities is caused by the fact that they usually succeed in discovering space-time structures which exactly correspond to the qualitative (now metrical) relations they are investigating, and space-time structures always lend themselves easily to quantification, i.e. description by means of numbers. The most typical example is the substitution of waves or vibrations for "colours". The reason why such a substitution of space-time structures for qualitative relations is possible lies in certain very general facts of experience which have something to do with what used to be called "psychophysical parallelism"; but we are not concerned with these matters here.
Thus the last argument in which the opposition of quantity and quality represents the opposition of form and content, is shown to be no better than all the others, which were directed against the view that all knowledge is purely formal. For us there can be no doubt that this view is right. But you will have missed the most important point of all if you do not see quite clearly that this view implies no resignation of any kind, that it does not restrict the field of knowledge in any way. If I have myself used the phrase that knowledge deals only with form, the "only" must not be understood as having a restrictive meaning, it is just meant to indicate a contrast with certain other current views. Not for one moment must we allow ourselves to think, or even to speak as if there were two realms in the world, a realm of form and a realm of content and that only the former could be known, whereas unfortunately our powers of knowledge were too weak to penetrate into the realm of content, so that we were forever condemned to stand longingly at its gate.
And it would be a still greater misunderstanding to believe that the gate was not irrevocably closed to the human mind, but that life and art and religion and metaphysics each were in possession of a key that would open the door for those who were able to find it, and that only poor science must always remain locked out because the unfortunate method it had adopted might be excellent for the discovery of outward structures, but utterly inadequate and helpless in any attempt to express the interior content of things. In reality of course, there are no two such fields of form and
