首楞嚴義疏注經 2.610

2.610

喻起妄也。妄本無因，故云無故。真妄和合，如二手相摩。阿賴耶識變起世間，故云生澁滑等。或可二手及空喻根境識，根境識三和合生觸，觸是受因，從此領納，故知受陰無明妄念，迷真和合，假託而生，故下破之。

This is a metaphor for the arising of delusion. Delusion fundamentally has no cause; hence it says 'without any reason.' The combination of the true and the false is like two hands rubbing together. The ālayavijñāna transforms and gives rise to the world; hence it says 'produces roughness, smoothness,' and so forth. Alternatively, the two hands and space can symbolize faculty, object, and consciousness; the coming together of these three—faculty, object, and consciousness—gives rise to contact (sparśa); contact is the cause of sensation (vedanā), and from this comes reception. Hence we know that the aggregate of sensation arises dependently from the deluded thoughts of avidyā confusing the true in combination. Therefore it is refuted below.