 While its role as a portrait frontispiece is typical of publications from the era , the exact circumstances surrounding the making of the engraving are unknown . It is uncertain which of two " Martin <unk> " created the engraving and it is not known to what extent the features were copied from an existing painting or drawing . Critics have generally been unimpressed by it as a work of art , although the engraving has had a few defenders , and exponents of the Shakespeare authorship question have claimed to find coded messages within it . 
