大方廣佛華嚴經隨疏演義鈔 27.9

27.9

Regarding the commentary's: “The heavens are a round dome”: non-Buddhist texts state that heaven is perhaps regarded as having form; thus they say that the shape of heaven is domed and vaulted, its shape like an overturned pot, hence “heaven is round and earth is square.” If according to Zhuangzi, who says “heaven is natural spontaneity,” then it has no shape or substance.