No death mask of Goethe's exists, in keeping with his explicit wishes. Death, he told Johannes David Falk in 1813 shortly after Wieland's death, “ist ein sehr mittelmäßiger Porträtmaler.” Although one occasionally finds mention of a death mask of Goethe in various collections, the masks which exist are life masks. Indeed, it has often been assumed that two life masks were made of Goethe, one in 1807 by Carl Gottlob Weißer and one in 1816 by Johann Gottfried Schadow. Only one mask and its copies have survived, however. One of the goals of Michael Hertl in his book is to argue that the surviving mask is clearly the one from 1807; there never was a mask made by Schadow. This discussion, however, comprises only one part of Goethe in seiner Lebendmaske, since Hertl also places the discussion of the authenticity of Goethe's life mask in the larger context of the history of life and death mask production in the Goethezeit.

Hertl, a professor of pediatrics and author of previous books on death masks in general and Nietzsche's in particular, uses modern medical technology to determine that the copies of Goethe's life mask all originate from the same mask, the one made by Weißer in 1807. Exact measurements from CT scans allow Hertl to demonstrate that not only are the copies of the masks all from the same original, but that Weißer also used Goethe's life mask in the creation of his bust of Goethe. At the same time that he discusses Weißer's life mask and the minute changes that were made to the original as copies were made, Hertl explains how it came to be that so many people assumed Schadow made a life mask of Goethe in 1816. Closely reading accounts of Schadow's visit to Goethe, Hertl notes that Schadow asked for and was granted permission to make a copy of the 1807 mask, an exemplar of which Goethe possessed. Thus, Schadow's work is a mask of a mask.

All of this is interesting medical detective work, but the book's interest to Goethe scholars lies more in the discussion of the significance of life and death masks in the eighteenth and nineteenth centuries. Goethe was intrigued by the new science of phrenology being advocated by Franz Joseph Gall (though it was Gall's assistant who coined the term).