It's an old saying..... from an old guy.
Way back in the 1900s, those Neanderthals who walked the earth actually left their phones in one place. Some even bolted them to the wall!!!! I must admit, I'm the offspring of such primitive beings. Those phones had access to exactly zero data...including the phone numbers of businesses and people nearby. As such, they relied on thick books which contained nothing but phone numbers.
Daryl Hall could turn to any page in that book and start riffing on it. It would groove.