 It is commonly believed that the early round coins of the Warring States period resembled the ancient jade circles (璧環) which symbolised the supposed round shape of the sky, while the centre hole in this analogy is said to represent the planet earth (天圓地方).The body of these early round coins was called their "flesh" (肉) and the central hole was known as "the good" (好).The hole enabled the coins to be strung together to create higher denominations, as was frequently done due to the coin's low value.