首楞嚴義疏注經 10.295

10.295

既稱為妄，云何有因？若有所因不名為妄，故云無因。自諸妄想展轉相因，交妄發生，遞相為種，故云於妄想中立因緣性。

Since it is called 'falsity,' how could it have a cause? If it had a cause, it would not be called falsity; hence it is said to have no cause. Since the various false imaginations mutually cause one another in turn, arising through intersecting falsity and serving as seeds for each other, it says 'within false imagination, the nature of causes and conditions is established.'