An extensive detailed commentary on the Emerald Tablet. Written by the Englishman John Garland also known as Hortulanus (c.1195 - c.1272). A partial English version was included in Roger Bacon, 'The mirror of alchimy', London 1597, summarising the work, but the text, here translated from a German edition is more detailed. It uses the structure of the well known 'Emerald Tablet of Hermes' to explore the main aspects of alchemy.