 Another contribution is related to motion in the void. Avempace analyzes “natural” movements such as a stone’s falling through air and water. They are the movements of the four elemental bodies: fire, air, water and earth. These movables need a moving power capable not only of moving them, but also of displacing the medium through which they pass. Dust particles stay suspended in the air because, although they possess enough power to go down, their power is insufficient to displace the air.