Today I found this in a free pile at the elementary school I visited today.
I fucking love this book.
Especially near the end when it says, "They (cats) bit and scratched and clawed each other and made such a great noise that the very old man and the very old woman ran into the house as fast as they could. They did not like such quarreling. But after a while the noise stopped and the very old man and the very old woman peeped out of the window to see what had happened. They could not see a single cat! ‘I think they must have eaten each other all up’ said the very old woman, ‘It’s too bad!"
PS: Fun fact Millions of Cats is the oldest American picture book still in print!