Read thus, the phenomenon tells us that a part of space occupied by a magnetic field has qualities which are otherwise found only where a coherent solid mass is present. A magnetic piece of solid iron, therefore, differs from a non-magnetic piece by giving rise in its surroundings to dynamic conditions which would otherwise exist only in its interior. This picture of the relatedness of magnetism to solidity is confirmed by the fact that both are cancelled by heat, and increased by cold.²