In Antiquity, glass, more than any known product of the earth, was a material that could be easily shaped and colored to imitate any precious stone or mineral substance; its natural lustre and transparency inspired ancient naturalists and philosophers at a very early stage to find an explanatory theory that could give a rational account of these marvellous properties. Such efforts increased after the technical revolution inspired by the introduction of glassblowing during the first century BCE, and were intimately connected with the history of alchemy.