I have brought together here the most important defects in Esperanto, the removal of which formed one of the tasks of the Delegation Committee. The knowledge of these imperfections does not prevent me from recognising the meritorious services of Zamenhof, who, at a time when the question of the best construction of an international language was not seriously discussed, succeeded in producing one which was in many respects superior to the attempts of that time, and which has proved in practice a serviceable, though very imperfect, means of international communication. OTTO JESPERSEN. CHAPTER IV ON THE APPLICATION OF LOGIC TO THE PROBLEM OF AN INTERNATIONAL LANGUAGE The problem of an international language has a theoretical as well as a practical importance. I have no intention of discussing the latter here and of explaining once more the necessity of an auxiliary language for international relations of every sort, and the practical possibility of making oneself understood by means of an artificial language, a possibility which has been proved by experience. But an international language is also, according to the words of the celebrated philologist H. Schuchardt, a desideratum of science, in which connection it raises at once problems of philology and logic. That these problems are worthy of the study of scientific men is proved by the discussions of Professors Diels and Gomperz, the reports made to the Academy of Sciences of Leipzig by Professors Brugmann and Leskien, and, finally, the labours and decisions of the Committee of the _Délégation pour l'Adoption d'une Langue Internationale_. The latter, composed of highly competent scientists and linguists, has determined the principles necessary for an auxiliary language, and has practically realised them. My desire in what follows is to show briefly the connection of the international language with logic, and its claims on the attention and interest of philosophers. In the words of Leibnitz, "Languages form the best mirror for the human spirit, and an exact analysis of the meaning and relationship of words would be the best means of disclosing the operations of the mind" (_N. Essais_, III., VII., end). But the majority of philosophers (with some distinguished exceptions, _e.g._, Professor Wundt) and the majority of linguists (also with some distinguished exceptions, _e.g._, M. Bréal) have given little attention to the study of language from the point of view of psychology and logic. Now this study is particularly easy and interesting in the case of an artificial language, since the latter presents a structure analogous to that of our existing languages, but much simpler and more regular.