The reason why a Waldorf doll uses only natural materials is because natural materials are infused with soul. Wool is warm, the doll radiates heat back to the child when it is held. The silk glows naturally, the wool has a sheen as does cotton. But mainly the argument for natural materials and in particular the plant dyed colors are that these cloths, yarns, stuffing once processed naturally will hold important soul enhancing forces drawn directly from nature. They are more beautiful to behold as well in their most natural form than something that has been synthetisized."