大乘起信論裂網疏 2.88

2.88

四、真實不空示現大義，如虛空明鏡。謂依離障法，隨所應化，現如來等種種色聲，令彼修行諸善根故。

Fourth, the great meaning of genuine non-emptiness manifesting, like space and a bright mirror. That is to say, relying on the phenomena free from hindrances, according with those to be transformed, it manifests various forms and sounds of the Tathāgata and others, causing them to cultivate all good roots.