For six years he worked at perfecting and testing it. This gave him plenty of work, notwithstanding he had considered it ready in 1878; but severe trials showed him that, although it might be ready in theory, it was not so in practice. He had much to cut out, alter, and radically transform. Words, forms, principles, and postulates opposed one another in practice, although each, taken separately, appeared in theory right. Such things as the universal preposition je, the elastic verb meti (to put), the neutral, but definite, ending aŭ, would probably never have entered his head had he proceeded only on theory. Some forms, which appeared to him to possess a mine of wealth, were shown in practice to be useless ballast, and, on this account, he discarded several unnecessary suffixes.
He had thought, in the year 1878, that it was sufficient for the language to have a grammar and vocabulary; the heaviness and want of grace of the language he ascribed to his not knowing it sufficiently well; but practice always kept convincing him that the language required an indescribable "something," a uniting element, giving it life and soul. He therefore avoided all literal translations, and commenced to think in the language.
He soon noticed that his new language was not a mere shadowy reflection of the language he happened to be translating, but was becoming imbued with a life and spirit of its own, and was now no mere lifeless mixture of words, It flowed of itself as flexibly, gracefully, and freely as his own native tongue.
However, another circumstance delayed for a long time its public appearance. He knew that everyone would say, "Your language will be useful to me only when the whole world accepts it, therefore I shall not learn it until I find everyone else is adopting it." This problem gave him much thought till at last it struck him that correspondence was carried on in cipher by means of a key possessed by both parties. This gave him his great idea, namely, to construct his language in the fashion of such a key by inserting in it not only the vocabulary, but the whole grammar in its separate elements. Such a key, alphabetically arranged, would enable anyone possessing the key, giving the meaning of the elements in his own language, to understand without further ado a letter written in Esperanto.
Dr. Zamenhof illustrates this in the "Krestomatio," page 249, by the following sentence:—"I do not know where I left my stick; did you not see it?" Now supposing that a German wished to write this to an Englishman or person of any other nationality, he would translate it from the German into Esperanto as follows, dividing the words into their elements by hyphens:—
Mi ne sci-as, kie mi las-is mi-a-n baston-o-n; ĉu vi ĝi-n ne vid-is?
The Englishman, on receiving the letter, turns to his Esperanto dictionary, or to the Ĉefeĉ Key, if it be enclosed, and reads as follows:—
| MI | = I | I | |
| NE | = no, not | not | |
| SCI- | = know | know | |
| -AS | = ending of present tense of verb | ||
| KIE | = Where | where | |
| MI | = I | I | |
| LAS- | = leave | left or have left | |
| -IS | = ending of past tense of verb | ||
| MI | = I | my | |
| -A- | = ending of an adjective (nom. case) | ||
| -N | = ending of the objective case | ||
| BASTON- | = stick | stick | |
| -O- | = ending of noun (nom case) | ||
| -N | = ending for the objective case | ||
| ĈU | = whether; asks a question | whether | |
| VI | = you | you | |
| ĜI- | = it (nom case) | it | |
| -N | = ending for the objective case | ||
| NE | = no, not | not | |
| VID- | = see | saw, or did see, or have seen | |
| -IS | = ending of past tense of verb |
The above, therefore, in bald English is "I not know where I left my stick; whether you it not have seen (or, did see)?" Now this is perfectly comprehensible to any Englishman. But some may say, "But if the German had written in his own language, and I had found a German dictionary, I could quite as easily have made out his meaning." Now the following is the German for this sentence:—Ich weiss nicht wo ich meinen Stock gelassen habe; haben Sie ihn nicht gesehen?
On referring to the German dictionary, and looking out the words, he would find:—ICH=I, WEISS=white, NICHT=not, WO=where, ICH=I, MEINEN=to think, STOCK=stick, GELASSEN=composed, calm, HABE=property, goods, HABEN=to have, SIE=she, her, it, they, them, you, IHN=(not in the dictionary), NICHT=not, GESEHEN=(not in the dictionary). Therefore the sentence would read:—I white not where I to think stick composed property; to have she (blank) not (blank).