首楞嚴義疏注經 2.131

2.131

此明緣心隨境往來，真心湛然常住。以客喻妄，以主喻真。

This clarifies that the conditioned mind comes and goes along with sensory objects, whereas the true mind is clear and permanently abiding. The guest is used as a metaphor for the false, and the host is used as a metaphor for the true.