A rare book, written in the 17th century and predicting alien life on Saturn and Jupiter, has been discovered in England – and now it may sell for thousands at auction.

Back in the dark ages, things were a lot simpler. Humanity knew its place in the universe, and that place was right in the center, surrounded by the orbiting Sun, Moon, six other planets, and eventually, some kind of large star-flecked dome that held the whole thing like a gigantic snow globe.

Then the scientific revolution happened, and everything was thrown into turmoil. The Earth’s place at the center of the Solar System had been usurped by the Sun, and worse still, some people had started suggesting that the universe might actually be bigger than just our little collection of planets. Suddenly, the Earth wasn’t the whole point of creation anymore – it was just one little rock in an infinite collection.

Which kind of raises an interesting conundrum. If you believe in God – and since it’s Europe in the 1600s, you almost certainly do – you have to think: what would be the point?

That was the starting point of the book, written in 1698 by the Dutch mathematician, physicist, astronomer and oft-forgotten second half of a space probe that died on Saturn in 2017, Christiaan Huygens. Why, he asked, would God create other planets “just to be looked” upon from Earth?

Surely, he reasoned, they must have some purpose – and that purpose must be to support life, he said.

“The book tries to describe what extra-terrestrial beings might look like, how they spend their time, even what their music sounds like,” said books valuer Jim Spencer, who found the tome at a free antique valuation event in a garden center in England.

“It seems almost comical, but it’s informed by scientific reasoning,” he added, “and who knows how our own thoughts on these matters will appear to people looking back in 324 years.”

So what did one of the greatest scientists of all time think aliens would look like? Well, they definitely have hands and feet: “What could we invent or imagine that could be so exactly accommodated to all the design’d uses as the Hands are?” he wrote.

“Shall we give them an Elephant’s Proboscis[?] ‘Tis true, these beasts can lay hold of, or throw any thing, can take up even the smallest thing from the Ground … But all this is nothing to those Conveniences the Hand is so admirably suted to,” he wrote. And “That they have Feet scarce any one can doubt …[unless] they have found out the art of flying in some of those Worlds.”

They’re also apparently quite the intellectuals: Huygens imagined them being astronomers and master navigators – “especially considering the great advantages Jupiter and Saturn have for sailing,” he noted, “in having so many Moons to direct their Course.” They “enjoy not only the Profit, but the Pleasures arising from [living in] a Society: such as Conversation, Amours, Jesting, and Sights;” they even enjoy music like we do, and must play musical instruments, he thought.

“It’s the same with Musick as with Geometry, it’s every where immutably the same, and always will be so,” Huygens wrote. “For all Harmony consists in Concord, and Concord is all the World over fixt according to the same invariable measure and proportion…if they take delight in Harmony, ’tis twenty to one but that they have invented musical Instruments.”

But life on other planets isn’t all some utopian vision, he warned. The inhabitants of Jupiter and Saturn must suffer “Misfortunes, Wars, Afflictions, Poverty,” he said, because “If Men were to lead their whole Lives in an undisturb’d continual Peace, in no fear of Poverty, no danger of War, I don’t doubt they would live little better than Brutes, without all knowledge or enjoyment of those Advantages that make our Lives pass on with pleasure and profit.” In other words: no pain, no gain.

The first edition book, described by Spencer as “really … an out-of-this-world find,” is set to be sold at Hansons Library Auction in Staffordshire, UK on July 5. If you want to put an offer in though, you’d better start saving now – its guide price is £2,000-3,000 (roughly $2,500-$3,750.)

“It’s a curious feeling when flicking through this book. The subject matter belongs to the future or science fiction, yet the writer is speaking to us from the past,” Spencer commented. “I found myself realizing that we’ve since explored not only more of space, but more of our own planet. For instance, he rules out the possibility of much larger animals than those here on Earth, but this was written before we’d understood anything of the dinosaurs.”

“The subject matter is so compelling,” he said, “because it makes us chuckle at what they didn’t know, while staring up at the heavens and realising it’s still a mystery.”