Everything on this web site is true.
How do you know it is true? Because this page tells you everything on the web site is true. And this page is part of the web site.
As the entire web site is true, then this page is also true. And every statement on this page is true.
Thus the claim on this page that everything on the site is true must be true.
That is just as true as any statement in a book claiming that the book is completely true.
