Sure, it's chapter 6 in POA titled "TALONS AND TEA LEAVES", I have the paperback version and its page 80. The sentence is "Many whitches and wizards, talented though they are in the area of loud bangs and smells and sudden disappearings, are yet unable to penetrate the veiled mysteries of the future,"...
That's the only mention of it, but it just caught my eye so thought I'd throw it into the ring of possibilities... I'm interested in your thoughts though.