Why It's Important
Grammar: a system of rules that determines (1) how the forms of words are made (e.g., swim, swam, swum), and (2) how words fit together to fit sentences.
The issue of how much attention to give grammar is perplexing. On the one hand, attention to correct grammar--and to spelling and usage--can seem terribly misplaced. After all, the main purpose of writing is to make meaning, isn't it? Worrying too much about grammar is worrying about minutiae and can bring on writer's block.
On the other hand, we know that it's important. In fact, it used to get a lot more attention in formal education than it does now. Consider, for example, the daily schedule which Guilford students followed in 1847:
5:00 a.m.— Rise, make beds, wash
6:00 a.m.— Grammar
7:00 a.m.— Breakfast
8:30 a.m.— Classroom studies
11:30 a.m.— Classes end for morning
12:00 p.m.— Lunch
2:30 p.m.— Classes resume
5:00 p.m.— Classes end for day
6:00 p.m.— Dinner
9:00 p.m.- Lights out
Grammar before breakfast!?! No wonder that in medieval classrooms, when grammar was even more prominent, the subject was personified as the goddess Grammatica, who was pictured as a severe old woman holding a scalpel and a large pair of pincers in her left hand. In her right hand, which was close by her side, she grasped a bird by the neck, its mouth wide open as if in a gasp or squawk.
It will probably surprise you to learn that in the earliest universities, grammar was one of only three subjects you studied to get a bachelor's degree. The other two were rhetoric and logic. Together these formed the "trivium" (from Latin tri "three" + via "road, way").
I should hasten to point out that "grammar" study meant more than memorizing punctuation rules. It chiefly involved the study of Latin, and because Latin was the main language of learned culture, grammar came to become synonymous with learning in general.
Still, however, study of language necessarily involves study of its rules, and that takes us back to the opening question—why should this be important?
Let me offer two reasons that should matter to you.