Ernst Marti devoted his life to researching the 'etheric realm' – a subtle area that exists between the physical and spiritual. Taking the numerous statements and references by Rudolf Steiner as his starting point, Marti develops our understanding of the etheric world in various fields – from the theory of knowledge to the natural world, through to music, the realm of colour, eurythmy and medicine. In doing so, he proposes exciting bridges from the ancient and medieval worldview to the present and future of natural and spiritual science. Having studied 'The World of the Ethers' in Vol. 1, here Dr Marti explores the 'The World of Formative (or Morphogenic) Forces'. Beginning with the sense qualities of the visible world, he studies the nature of sense perception, the origin of morphogenic forces and their phenomenology. In three key sections he examines the formative forces of shape or form (including the growth movements in plants and how they relate to eurythmy and the forces of colour); the formative forces of life (the planetary origin of the morphogenic forces of life and the seven life processes and their relation to rhythm; and the formative forces of substance (the zodiac and the planets and the formative forces of metals). In this concluding volume of his seminal work, Marti also offers pertinent comments on the nature of potentization in medicine.