大乘起信論裂網疏 5.81

5.81

二、釋解行發心者，夫論稱性圓修，則即信即解即行即證。故云：初阿字中即具一切諸字功德。縱分四十二位，譬如入海而論淺深，淺深皆海，豈有無解行證而可名信？豈令解行與證定居信後？特以實位難測，寄權易明，故次信而辨解行也。文為二：初、明位；二、明行。今初。

Second, as for explaining the arousal of the mind through understanding and practice: in terms of the complete cultivation according with nature, faith itself is understanding, is practice, and is realization. Hence it is said: "The initial letter A already possesses the merits of all letters." Even though forty-two stages are distinguished, it is like entering the sea to discuss shallowness and depth—both shallow and deep are the sea. How could there be faith without understanding, practice, and realization? How could understanding, practice, and realization be made to reside strictly after faith? It is solely because the real stages are difficult to fathom, whereas relying on the provisional makes them easy to clarify, that understanding and practice are distinguished following faith.

The text has two parts: first, clarifying the stages; second, clarifying the practices. Now, the first.