首楞嚴義疏注經 1.391

1.391

因心所兼，根塵相雜，塵亦分別，根亦無知。物即塵也，體即根也。

Because of what the mind combines, the faculty and dust become mixed together: the dust would also discriminate, and the faculty would also lack sentience. 'Thing' is the dust; 'substance' is the faculty.