That reminded me of the following bedtime story I used to read to the son of two of my friends when he was about 3 or 4 years old...
I actually found the book of it in a pile of other books that were in a number of black bin bags in the outhouse of a house in the Lake District in England that one of my sisters and her husband were renting whilst their own house was being renovated. They had been told to take any of the books they wanted, as the bin bags were going to be donated to charity. That particular edition of the Millions of Cats book had been printed in 1939.
It quickly became a story that I would read it to him as one of his bedtime stories any evening I went round for dinner (or supper, as it was called at the time, because after it he was expected to get into his pajamas). Whenever we got to the 'hundreds of cats, thousands of cats, millions and billions and trillions of cats!' parts he would join in all excitedly. Of course, he had no idea at the time what a thousand meant, let alone million or billion or trillion. Indeed, he couldn't even count up to a hundred....
It became his go-to bedtime story until he was about six years old, when he discovered the Harry Potter books. I think only the third or fourth Harry book had been written at the time, but he became that engrossed by them that he was annoyed at the fact that we couldn't read them fast enough for him, and so it actually accelerated his learning to read for himself. As his mother said one time, when I commented on his sudden improvement in reading: "We can thank J.K. Rowling for that."
I actually still have a photograph on my mantelpiece, that his dad took one evening, of him in his pajamas sitting on my knee, and me sitting in an armchair with that book open as I was reading it to him.
He's twenty-one years old now. Next time I'm round I must ask him if he still remembers Millions of Cats being his favourite bedtime story...