Why is it not enough to make the ink stone into a foot shape?

Social ethics in the Han Dynasty is still in the era of respect for heaven, God, ghosts, Han aesthetic style of utilitarianism is also embodied in the rituals and mysticism carried in these shapes, patterns and other artifacts. Lacquer, pottery and other imitation of bronze rituals, are three-legged, so it is not surprising that the ink stone made of tripod-shaped.