Why are ancient copper coins round with squarish centre?

“Our ancestors told us, “Copper coins are round outside and have a squarish center.” This implies that when we do things, our mental state should be rationale inside (signifying squarish center). When we face external circumstances, we should try to perfect all our life circumstances and make them wholesome. (signifying round circumference)  We should not be flustered and this is very important. This is in accordance with our cultivation. If we become flustered, our cultivation and aspirations will be difficult to fulfill.”"

Zen Master Wu Jue Miao Tian

【 禪師說禪 】修行之道：外圓內方

老祖宗告訴我們，古代的銅錢都是外圓內方，意味著我們做人做事時，心裡要有原則，但對外要圓融世法，保持心不慌亂，這是很重要的，與修行相關，不能本末倒置，否則心亂了，修行就不能如願。

講述／悟覺妙天禪師

To read more:

https://www.zencosmos.com.tw/2017/12/master/11448/ 

Reference:

https://www.facebook.com/zencosmos/posts/1912060858811902