肇論新疏 3.143

3.143

經即《太子本起瑞應經》也。菩提祕藏中般若故。圖度，思慮也。何故不可耶？以高而無上等。謂高深有際可思，上下無窮，故不可也。天地至大，智又包含；無間至小，智復入中。無間，如子微極細，無中間也。以證涅槃體大用廣。

The scripture is the *Taizi benqi ruiying jing*. It is prajñā within the secret treasury of bodhi. 'Conceived or measured' means thought and deliberation. Why is it impossible? Because it is high without an above, and so forth. That means where high and deep have boundaries, they can be thought; where above and below are inexhaustible, it is impossible. Heaven and earth are of utmost greatness, yet wisdom further encompasses them; where there is no space between is of utmost smallness, yet wisdom further enters into it. 'No space between' is like the infinitesimal particle, which has no intermediate gap. This proves that the substance of nirvāṇa is great and its function is vast.