Earth - Ref
Creatures of the earth. Leonardo de Piero Dati, La sfera. Wellcome Library MS 230 (mid 15th century), f.8v
The part of the world below the sphere of the moon was subject to constant change. As the heaviest element, the sphere of earth was located lowest down, that is in the centre. The qualities of this element are cold and dry and its humour is black bile.