首楞嚴義疏注經 2.35

2.35

此至細而觀也。若以沈靜其思審諦觀察，即剎那不停，念念流變，此即微細四相遷流不息。凡夫心麁，殊不知覺。古德偈云「如以一睫毛，置掌人不覺，若置眼睛上，違害極不安。愚人如手掌，不覺行苦遷，智者如眼睛，違極生厭患。」言剎那者，時之極少也。《俱舍論》說「時之極少名曰剎那，時之極長名之為劫，乃至年之與月俱是時之分劑。」又云「百二十剎那為一怛剎那，六十怛剎那為一臘縛，三十臘縛為一須臾，三十須臾為一晝夜，三十晝夜為一月，十二月為一年，十二年為一紀。」前約十年為限，是約一紀舉全數爾。

This is contemplation down to the ultimate subtlety. If one quietens one's thought and attentively observes, then without stopping for a kṣaṇa, from thought-moment to thought-moment it flows and transforms; this is the subtle four characteristics shifting and flowing without rest. Ordinary beings have coarse minds and are utterly unaware of it. A verse by an ancient master of virtue says: 'As a single eyelash / Placed on the palm is not noticed, / If placed upon the eye / It causes extreme distress and harm; / An ignorant person is like the palm of the hand, / Unaware of the shifting suffering of conditioning; / A wise person is like the eye, / Distressed to the utmost, giving rise to revulsion.' As for the term kṣaṇa, it is the minimal unit of time. The Abhidharmakośa-bhāṣya states: 'The minimal unit of time is named a kṣaṇa; the maximum unit of time is named a kalpa; up to years and months, all are divisions of time.' It also says: 'One hundred and twenty kṣaṇas make one tatkṣaṇa; sixty tatkṣaṇas make one lava; thirty lavas make one muhūrta; thirty muhūrtas make one day and night; thirty days and nights make one month; twelve months make one year; twelve years make one cycle (ji).' The earlier demarcation by ten years was simply taking a round number for a cycle.