An "incredibly scarce" first edition of a Sir Isaac Newton book has sold at auction for £24,000.
The copy of Mathematical Principles of Natural Philosophy in English, published in 1729, was given a guide price of between £8,000 and £10,000.
It is the second copy to fetch more than £20,000 in recent weeks following a lockdown discovery in Wales.
The anonymous Guernsey seller said the book had been in the family's possession for about 60 years.
Auctioneer Jim Spencer said he "couldn't believe it" when the book arrived at his office during the lockdown.
"I was just thrilled to hold something of such significance in my hands - what an honour to catalogue this," he said.
Newton's Mathematical Principles of Natural Philosophy laid the foundations of his theory of gravity and is often described as the greatest work in the history of science.
The Channel Islands seller, who did not wish to be named, said their grandfather had obtained the copy in the 1950s and left it to them on his death in 1980.
Mr Spencer, book expert of Hansons Auctioneers in Staffordshire, described it as an "incredibly scarce book" of which "perhaps only a few hundred were printed".
"The very first edition of Newton's Principia was published in 1687 in Latin and a copy sold in recent years for millions of dollars.
"This is the first edition in English, translated by Andrew Motte, and is such an important thing."
The item was auctioned online on Tuesday and sold to a European buyer.