首楞嚴義疏注經 6.334

6.334

圓通即是心所行路，故云心迹。領悟既深，得無疑惑；未來多難，更欲伸陳。悲欣者，欣今所悟，悲後行人。

Perfect penetration is the path traversed by the mind, hence it is called "the trace of his mind." Having understood so deeply, he attained freedom from doubt; yet because the future will hold many perils, he wished to speak further. "Sorrow and joy": he rejoiced in what he now understood, and sorrowed for future practitioners.