Basilius Valentinus (also known under the Anglicised version of his name, Basil Valentine) is shrouded in mystery. It is said that he was a 15th century alchemist and there are also claims that he was the canon of the Benedictine Priory of Saint Peter in Erfurt, Germany - a claim that cannot, so far, be substantiated. All that can be said for certain is that numerous publications on alchemy were published in both Latin and German under the name of Basilius Valentinus, many of which were widely translated into various European languages. What makes this edition so special are the additional treatises by both John Holland and Roger Bacon. John Isaac Holland (active 1572-1610? ) was a Dutch alchemist who is thought to have lived in the 15th century. It was said that he was the first alchemist of Holland. Roger Bacon, (c. 1214-1294), also known as Doctor Mirabilis (Latin: "wonderful teacher"), was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empirical means.