The Mutus Liber (Latin: silent book) is a book of alchemical illustrations first printed in 1677. The authorship of the book is uncertain.

According to Adam McLean, a renowned authority and
scholar of alchemical manuscripts and illustrations,
"authorship is assigned to an anonymous figure named 'Altus'-'the high, deep and profound one'."

The book consists of a series of 15 enigmatic illustrations depicting the work of alchemists. The book appears to illustrate the nature of the Great Work in a series of step by step instructions.