Conversely, this great process of purification cannot fail to bring to light much that is of value for the theory and systematisation of scientific concepts. For one must be quite clear on a subject oneself before one can make it clear to others. Indeed, even a simple classified list of possibilities, in which one has earnestly sought to omit nothing of importance, constitutes in itself a scientific advance, which is rendered all the more desirable by the fact that in general people have troubled very little about questions of this sort. It may be already foreseen, and indeed with pleasure, that such problems are not to be solved offhand, and will probably require for their final settlement an international congress, at which the final decisions will be made. For this congress will probably be the first scientific gathering at which, instead of three, four, or five languages, only one, and that the international auxiliary language, will be spoken. WILHELM OSTWALD. CHAPTER VII CONCLUSION: READING, WRITING, AND SPEAKING Anyone who wishes to swim without the help of others is faced by a "vicious circle." In order to swim he must jump into the water, but before he entrusts himself to the water he ought to be able to swim. In spite of this, many people learn to swim without a teacher. How do they do that? They go at first only into shallow water, and splash about there until they have become more or less familiar with this element. Then, when they perceive that they can propel themselves in it, they go gradually into deeper water. If we wish to get scientific men to use the international language, we must probably recommend the same method and advise them to move about in the shallower regions of every-day language before they venture into the deeper waters of science. The instruction concerning the movements of swimming given by the swimming-master on dry land corresponds to a lesson of a couple of hours on the simple grammar of the international language. Further progress, leading up finally to the introduction of the latter into science, can be divided into three stages, which we may describe by the words reading, writing, and speaking.