What evidence do you have that there is not an invisible unicorn in your room right now?

If you can't disprove it then it must be true. It was written in the book of the unicorn that "Lo, the mighty invisible unicorn shall be born and he will look kindly on those who leave invisible hay by their bedsides." The invisible unicorn loves us and wants us to abandon those other false mythological beasts. All the magical creatures in Harry Potter are heresy. Let's boycott Warner.