肇論新疏 1.301

1.301

何則？欲言其有，有非真生；欲言其無，事象既形。象形不即無，非真非實有。然則不真空義顯於茲矣。

Why is this? If one wishes to speak of their being, their being is not truly produced; if one wishes to speak of their non-being, the forms of things have already taken shape. Forms having shape is not immediately non-being; not being true is not real being. Thus the meaning of the emptiness of the unreal is revealed here.