Based on the stylistic analysis of the Calvary at Tallinn’s Cathedral, it can be said that adherence to nature was one of Ackermann’s creative principles. Adam’s skull and shinbones which were added to the Calvary provide an especially convincing affirmation of this. The skull and the shinbones are so realistically carved and so true to nature that the question arises whether the master used printed models or genuine human bones as a reference for carving the skull and bones.