Grammar is a mental machine which takes our thoughts and makes them comprehensible to others.
Thoughts are made up of emotions, reactions, fears, anticipations, sensual pleasures, predictions, will, history, intuition, and a lot more. Grammar is an arbitrarily created mechanism for organizing these various ingredients into a regularized system which can be accessed by anyone who knows how this mechanism works. The ingredients of all languages are the same (nouns, verbs, adjectives, exclamations, tones, dynamics, sounds and so on) but they are packaged differently in each linguistic group.
Humans have wrought clever variations, and each variation has a variation, so my examples are general. To create the plural English uses an “s” on the end of words, Italian an “i” or an “e,” Hebrew an “im,” and some languages say “book-book” to indicate two books. The Slavic languages don’t usually use the articles “the” and “a[n]”, even after they learn English. My Ukranian doctor says, “I will bring you book.” The only thing that remains sacred is that there are always nouns, verbs, adjectives, adverbs, exclamations, etc.
Spanish uses the reflexive frequently: Se va al Mercado? literally translated is Is one going to the market? but in English it means, Are you going to the market?
Some languages, like Irish, put the verb before the subject” D’imigh na fir is literally, Left the men,” but in English we would say, The men left.
Chinese is a maze of building blocks: Zhangsan yiwei Lisi mai-le shenme Literally means Zhangsan think Lisi bought what and in English would be What does Zhangsan think Lisi bought?
Even a closely related language like French is surprisingly eccentric when translated literally. Je ne l’ai pas vu is literally I not it have not seen. Recently, the French have been simplifying this to Je ne l’ai vu.
English has twisted itself around grammatically since the time of Beowulf, and we are still evolving. One example is the now-common format, Me and Mary went to the mall. English speakers assume that the first word in a sentence is the subject, and while the sentence grates on the senses of older people, we do understand the meaning. Freshman college students in my writing classes (even my own daughter) use this format when speaking, though not so much when writing.
The linguistic trend is toward simplicity. Ancient languages like Sanskrit had multiple forms for the noun and the verb, but now we have deemed even the I superfluous in the sentence Me and Mary went to the mall. Me has gobbled up I like a linguistic pacman or zombie. Some ancient forms persist. In modern Greek, they still use the vocative when addressing someone directly.
If the goal of good grammar is perfect understanding, then Me and Mary went to the mall is acceptable. The aesthetics are subjective, and when the rest of us are dead, who knows what the young people will do! Imagine the many generations of grandparents and parents from Shakespeare’s day who would be turning over in their graves if they could hear how their beloved language is spoken today.
Wittgenstein nailed it, …the harmony between thought and reality is to be found in the grammar of language. A thought in your own head has no power. In order to connect it to the world around you, it must be presented in a form others can understand, and that is why we need grammar. We are capable not only of learning other languages’ grammar, but we are also constantly reshaping our own.