For all these languages the above numbers are relatively higher than in the case of Esperanto. One of the most effective means of simplifying the vocabulary of a language is a carefully worked-out system of word formation, which enables everyone, by means of a series of regular prefixes and suffixes, to form with the greatest ease a large number of new words, which are immediately intelligible to all who know the rules. When one has judiciously chosen the roots which occur under different forms in the various natural languages and also selected the derivative terminations with all possible care, it is astonishing to observe how great a number of words derived with perfect regularity agree with the forms occurring in living languages. With regard to grammar, the fundamental condition to be required of every system claiming to be an international language is that of perfect regularity. Every exception to the rules only serves to produce complications and to render the employment of the language difficult and uncertain. If one knows the conjugation of one verb, one must know the conjugation of all verbs, and so on. In the choice of grammatical terminations the statistical method, which served us for the purpose of the vocabulary, cannot be strictly applied, because living languages diverge too much in this matter. Nevertheless it does not leave us entirely in the lurch. Such cases as the dative and genitive and also the ablative, etc., must be expressed by prepositions in conformity with the tendency of Western European languages. It is advisable to have an inflection for the accusative, although this is only intended for occasional use, because in the great majority of instances there is no necessity to distinguish it from the nominative. As neither the Romance languages nor English and Scandinavian possess any accusative inflection, and as the Slavonic languages do not give us any help here, we are obliged to fall back on German, which in the feminine and neuter has no inflection. The masculine, however, in many cases has an _-n_ (_den guten knaben_). The fact that this termination is also mostly used for the dative, as well as for the infinitive, need not prevent us employing it in our language for the accusative. It necessitates the use, however, of forms ending in a vowel for the nominative of substantives (and adjectives and pronouns). It may be remarked that _-n_ as an accusative inflection is also found in Greek and Finnish.