A reader of the post on the uses of the past participle wonders,
How did English come to require helping verbs? Isn’t that unusual among languages?
Helping verbs are not unique to English. Also called “auxiliary verbs,” helping verbs are common in analytical languages like English. (An analytical language has lost most of its inflexions.) Auxiliaries are used with main verbs to help express grammatical tense, mood, and voice.
tense: forms or modifications (or word-groups) in the conjugation of a verb to indicate time (past, present, or future).
mood: a form or set of forms of a verb in an inflected language, serving to indicate whether the verb expresses fact, command, wish, conditionality, etc.; the quality of a verb as represented or distinguished by a particular mood. For example, the sentence “Get thee gone!” is in imperative mood because it expresses a command. For the difference between tense and mood, see ”Mood vs Tense.”
voice: a category used in the classification of verb forms serving to indicate the relation of the subject to the action. For the difference between active and passive voice, see “Verbs Voice.”
A highly inflected synthetic language like Latin, on the other hand, combines tense, mood, and voice into a single compounded word.
Take, for example, the English sentence “I had sung.” Each of the three words conveys a significant piece of information. The free-standing pronoun I identifies the subject as the speaker; the past participle form sung, with the helping verb had, places the action in the past previous to another action. All of these ideas are expressed by one Latin word: cantaveram.
Helping verbs rock.