"John Ronald Reuel Tolkien wrote his first story aged seven. It was
about a 'green great dragon'. He showed it to his mother who told
him that you absolutely couldn't have a green great dragon, and that
it had to be a great green one instead. Tolkien was so disheartened
that he never wrote another story for years.
The reason for Tolkien's mistake, since you ask, is that 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."