Whisky is the liquid gold that emerges from the distillation of base beer. It is "the separation of the gross from the subtle and the subtle from the gross ... to make the spiritual lighter by its subtlety" (Hieronymus Brunschwig, 15th century doctor and distiller). Almost all spirits are produced by distillation: a liquid with a low alcohol content such as wine or beer can be taken and from it a spirit produced. Alchemists believed that through repeated distillation they could extract the essence or spirit of a material and that from wine they could extract the aqua vītae or water of life. The word itself, whisky, is an Anglicised version of the Gaelic for water of life: uisge beatha or usquebaugh is what Irish and Scots monks called their distilled barley beer.