This  sale of a rare 16th-century astronomy book titled "The Castle of Knowledge," written by Welshman Robert Recorde. The book, published in 1556, also happens to be the first edition and was sold at auction for £10,000.

Robert Recorde, known for inventing the equals sign (=), was born in Tenby, Pembrokeshire, in 1510. The book predates the birth of Italian astronomer Galileo, who is often regarded as the father of observational astronomy, by eight years.

The discovery of this first edition of Recorde's work was a significant find for Hansons Auctioneers, who described it as "amazing." The book, notable for being the first astronomical treatise published in English, is considered a rare and important scientific text. Auctioneer Jim Spencer noted that such copies coming up for sale are exceptionally rare.

The book's condition was well-preserved, although some leaves were lost over time. Despite these flaws, its scarcity and importance in the history of astronomy and mathematics make it highly collectible.

Robert Recorde's contributions to mathematics, including introducing the plus (+) and minus (-) signs to English speakers in 1557, are notable. However, he is relatively less known than other famous scientists like Galileo and Isaac Newton. Recorde's life ended tragically as he died in jail.

This discovery and sale shed light on the significance of Robert Recorde's work and contributions to mathematics and astronomy during the 16th century.