Hastings' Dictionary of the Bible (1898)
FOOT'STOOL. 2 Chr 9:18. Kings and other rulers sitting in state required a stool upon which to rest their feet. The divine glory, which resided symbolically in the holy place between the cherubim above the ark, is supposed to use the ark as a footstool. 1 Chr 28:2; Ps 99:5. So the earth is called God's footstool by the same expressive figure which represents heaven as his throne.