Looking for this book with ‘Myth’ in its title

I'm looking for this apparently famous classic book that has 'Myth' in its title. I can't recall the exact name of the book.

I do know that the book is about the idea of myths, not the myths themselves. Just to eliminate other suggestions, I'm not looking for MYTHOS (Fry) or MYTHOLOGY (Hamilton).

Also, this book that I'm searching, I'm vaguely remembering it has multiple editions or maybe multiple volumes or something like that. That's all I can recall.

Help would be greatly appreciated.