In this Alchemical Engravings of Mylius, we see what might be described as kings and queens sitting in a tree. Carl Jung notes that for the alchemist the tree is often related to the union of opposites. In this image, the kings and queens may represent the opposites as well. In The Archetypes and The Collective Unconscious, Jung says:
“The alchemist saw the union of opposites under the symbol of the tree… the symbol of the cosmic tree rooted in this world and growing up to heaven-the tree that is also man. In the history of symbols this tree is described as the way of life itself, a growing into that which eternally is and does not change; which springs from the union of opposites and, by its eternal presence, also makes that union possible.” (Carl Jung, CW 9i, para. 198).
Carl Jung, The Archetypes and The Collective Unconscious (Collected Works of C.G. Jung Vol.9 Part 1) ,