Even God has been proven to not exist because of the existence of the Babel Fish. The Babel Fish, when inserted in your ear, let's you understand all languages. According to the Guide, "The Babel Fish is small, yellow and leechlike, and probably the oddest thing in the Universe Now it is such a bizarrely improbable coincidence that anything so mind-bogglingly useful could have evolved purely by chance that some thinkers have chosen to see it as a final and clenching proof of the non-existence of God. The argument goes something like this: "I refuse to prove that I exist," says God, "for proof denies faith and without faith I am nothing." "But," says Man, "the Babel Fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED."" After all this adventure through the far reaches of space the only thing that crew wants is a nice hot meal at the most popular, and farthest away, resturant, the Restaurant at the End of the Universe.
This book has some of the most ironic yet sensible symbols in a modern book. Take the color yellow. In chapter one Arthur sees yellow bulldozers outside his window. Yellow ships are also waiting above the Earth to bulldoze it. Yellow usually symbolizes knowledge, learning, and joy, but can also mean jealousy and persuasion. The fact that something yellow is about to bulldoze his home and his planet is a very good example of an oxymoron. Another symbol used in the book is Thursday. We aren't given any real month or even season that the Earth id destroyed, but we do know it was on a Thursday. There are other significant Thursdays, especially in Christianity. Some of which are Assent ion Thursday and Thanksgiving. It also seems ironical that a day that usually means saving and kindness is the day chosen for the Earth to be demolished. This all of course goes along with the theme of the book, which would be the Infinite Improbability Drive.