The evolution of language is a story of progressive simplification: that is to say, the further back we go in the study of languages that are most closely related to English, the more complex the linguistic structure seems to be. Latin, for example, has inflections (multiple word endings depending on the word’s context) of nouns, pronouns, verbs, as well as adjectives.
In this process of simplification, English has come further than any other European language. Inflections of nouns have been reduced to a single letter sign for the plural and a punctuation mark to form the possessive case. Pronouns, which in Latin could be understood from the verb ending as well as a wide array of declining pronouns, have their own possessive forms in English but rarely change according to the word’s role in the sentence. The elaborate Teutonic inflection of adjectives has been entirely eliminated, except for the simple indication of the comparative and superlative degrees by ‘-er’ and ‘-est’ suffixes. Verbs have been simplified by the loss of practically all the personal endings, the near-complete abandonment of any distinction between singular and plural, and the gradual obsoleting of the subjunctive mood.
So while English vocabulary has expanded exponentially, the actual form of the language from its many derivative roots has essentially been simplified – although that still doesn’t help us with the often baffling rules of spelling and pronunciation!