Einar Jónsson envisioned Natura Mater (Mother Nature) as a monument for a mass grave. The subject links itself to the Egyptian and Greek myths of the Sphinx, a curious animal with the face of a woman and the body of a lion. This motif appears in the works of various artists around the turn of the 19th century. Most often the subject is of the duality of the sphinx, whereas she is a giver but also takes. A similar idea lies behind Natura Mater, where nature both gives life and takes life away. The work depicts a sphinx in a knelt down position, a man and woman draped over her paws, with their arms crossed on her bosom, both suckling for nourishment. Beneath the paws of the sphinx lie the bodies of deceased figures, their arms also crossed. The face of the sphinx is expressionless and shows no emotion. From her shoulders rises a Cyprus, the symbol of both growth and death. Along the sides of the piece are small murals, on one side depicting herbivores like horses, giraffes, elephants and camels, and on the other side carnivores, among them man. Opposites meet through this artwork; they are dependent on each other and constitute the circular motion of life. The artwork is placed upon a pyramid-shaped pedestal, linking the piece more closely to the Egyptian sphinx.