English is a language of exceptions, with few concrete rules. When it comes to adjectives, however, there is a very specific hierarchy most English speakers know, instinctively, must be followed to avoid utter confusion. Those rules may be broken only at great risk — including the risk of derailing one of the greatest literary geniuses in history.

According to Mark Forsyth’s book The Elements of Eloquence: Secrets of the Perfect Turn of Phrase, “adjectives in English absolutely have to be in this order: opinion-size-age-shape-colour-origin-material-purpose Noun. So you can have a lovely little old rectangular green French silver whittling knife. But if you mess with that word order in the slightest you’ll sound like a maniac. It’s an odd thing that every English speaker uses that list, but almost none of us could write it out. And as size comes before colour, green great dragons can’t exist.”

The reference to green great dragons is significant and almost changed the course of English literature. J.R.R. Tolkien wrote his first work of fiction at the age of seven. The story featured a “green great dragon,” but when his mother read it, she corrected him, telling him that there was no way one could have a “green great dragon;” he would need to change it to a “great green dragon.”

The young boy, who would eventually become immortalized as the author of The Hobbit and the Lord of the Rings trilogy, was so discouraged by this revelation that he put his fledgling work aside and did not make another attempt at writing for years.