Arnaldus de Villa Nova (1235-1311), Spanish alchemist. Arnaldus is shown here with the figures of Thabritius and Beya, the son and daughter of the king of the sea. Their incestuous union is seen during the first vision of Arisleus and is meant as an allegory of the way by which the Philosopher's Stone is made by alchemy, the conjunction of two parts of a whole. Arnaldus was a scholar and physician who translated many important texts from the Arabic including those by Avicenna and Galen. He conducted early experiments in chemistry and is credited with discovering carbon dioxide and ethanol. This engraving comes from 'Symbola aureae' by Michael Maier, published at Frankfurt in 1617.