Esperanto famously offered a language whose grammar was so simple that it could be amply summarized in sixteen rules (reproduced here from Edward A. Millidge’s Esperanto-English Dictionary) and learned in a short amount of time:
There is no indefinite Article; there is only a definite article (la), alike for all sexes, cases, and numbers.
Remark. — The use of the article is the same as in the other languages. People who find a difficulty in the use of the article need not at first use it at all.
Substantives have the termination o. To form the plural the termination j is added. There are only two cases: nominative an accusative; the latter is obtained from the nominative by the addition of the termination n. The rest of the cases are expressed by the aid of prepositions (the genitive by de, the dative by al, the ablative by per or other prepositions according to sense.
The Adjective ends in a. Case and number as with substantive. The Comparative is made by means of the word pli, the Superlative by plej; with the Comparative the conjunction ol is used.
The cardinal Numerals (they are not declined) are: unu, du, tri, kvar, kvin, ses, sep, ok, naŭ, dek, cent, mil. The tens and hundreds are formed by simple junction of the numerals. To mark the ordinal numerals the termination of the adjective is added; for the multiple — the suffix obl, for the fractional — on, for the collective — op, for the distributive — the word po. Substantival and adverbial numerals can also be used.
Personal Pronouns:mi, vi, li, ŝi, ĝi (referring to thing or animal), si, ni, vi, ili, oni; the possessive pronouns are formed by the addition of the adjectival termination. Declension is as with the substantives.
The Verb undergoes no change with regard to person or number. Forms of the verb: time being (Present) takes the termination -as; time been (Past) -is; time about-to-be (Future) -os; the Conditional mood -us; the Ordering mood -u; the Indefinite (Infinitive) mood -i. Participles (with an adjectival or adverbial sense): active present -ant; active past -int; active future -ont; passive present -at; passive past -it; passive future -ot. All the forms of the passive are formed by the aid of a corresponding form of the verb esti and a passive participle of the required verb; the preposition with the passive is de.
Adverbs end in e, degrees of comparison as with the adjectives.
All the Prepositions require the nominative.
Every word is read as it is written.
The Accent is always on the penultimate syllable.
Compound words are formed by simple junction of the words (the chief word stands at the end); the grammatical terminations are also regarded as independent words.
When another Negative word is present the word ne is left out.
In order to show direction words take the termination of the accusative.
Each Preposition has a definite and constant meaning: but if we have to use some preposition and the direct sense does not indicate to us what the special preposition we are to take, then we use the preposition je, which has no meaning of its own. Instead of the preposition je the accusative without a preposition can also be used.
The so-called foreign words, that is, those which the majority of languages have taken from one source, are used in the Esperanto language without change, merely obtaining the spelling of the latter; but with different words from one root it is better to use unchanged only the fundamental word and to form the rest from this latter in accordance with the rules of the Esperanto language.
The final vowel of the substantive and of the article can be dropped and be replaced by an apostrophe.
To this brief grammar is added a system of correlative words that have their own, special terminations that do not appear elsewhere, but whose consistency unto themselves makes them fairly easy to learn:
each one, each; everbody, all the...
no one; no...
that one; that...
no one’s, nobody’s
in every way
how, as, like
in no way
some kind of
every kind of
what kind of? what a...!
no kind of
some amount; somewhat
how much, how many
for some reason
for every reason
for no reason
All this is explored in more detail in the following pages.