首楞嚴義疏注經 2.106

2.106

The tathāgatagarbha has four meanings, hence it is compared to the sea: forever transcending the hundred negations, like the sea is extremely deep; containing the myriad existents, like the sea is vast; devoid of any virtue it does not possess, like the sea has precious gems; devoid of any dharma it does not manifest, like the sea manifests images. Its substance is serene and still, not associated with defiled falsity; hence it says "clear and still," which is the former meaning of extreme depth. "Hundreds of thousands" is the former meaning of vastness. Not recognizing that it is the originally pure substance, it therefore says "abandoning it." Only taking the turbidly agitated appearance to be the nature of mind, it therefore says "only recognizing," and so forth. "Entire tide," "great ocean," and "seas" are all different names for the sea.