When most people read novels, they probably aren't thinking much about how many commas or quotation marks each sentence contains. Generally, punctuation exists to make the process of reading easier, to smooth the flow from sentence to paragraph to page. When done well, punctuation almost disappears into the background, leaving the reader (copy editors aside) to focus on the words.

But as Princeton scientist Adam Calhoun recently found, the punctuation that writers use — and the frequency with which they use it — can reveal as much about their writing style as their word choice.

Calhoun decided to strip the words from his favorite texts to look at the punctuation alone, and noticed a few significant differences among great works of literature. Here, for instance, is a passage from Cormac McCarthy's Blood Meridian (on the left), compared with one from William Faulkner's Absalom, Absalom!

As is obvious even from the two books' titles, Faulkner is much more generous and varied with his punctuation; his writing is stuffed with parentheses, quotation marks, and even semicolons, while McCarthy's largely sticks to placid periods, commas, and question marks.

Calhoun also surveyed the frequency of various punctuation marks in several different books. He found, fittingly for Ernest Hemingway's famously straightforward, declarative style, that A Farewell to Arms is short on the exclamation points and generous with the periods. And the oft-misused semicolon seems to get less popular over time; compare Pride and Prejudice (originally published in 1813) with Blood Meridian (1985).

If you prefer your punctuation visualizations a bit more colorful, Calhoun also turned his findings into "heat maps" by representing periods, question marks, and exclamation marks in red, commas and quotation marks in green, and semicolons and colons in blue.

It's a fascinating way of thinking about literature and how rich and varied the English language is — right down to the humble comma. Check out Calhoun's Medium post to see more cool visualizations of how writers use punctuation.