大般涅槃經集解 61.96

61.96

案僧亮曰：為因性得果為譬也。業非內外者，如施非獨我，故非內。得非受者，故非外也。是二中間不可得故，非有非無也。施從因得，非本無今有。不從外來，非無因出也。滅故不一，非此作此受。續故不異，非此作彼受也。由因得果，非無作無受。以時節和合，須眾緣和合得果報也。

Sengliang comments: "This is a metaphor for the nature of the cause obtaining the fruit. That 'karma is neither internal nor external': like giving, it is not solely oneself, hence not internal; the attainment is not the recipient, hence not external. Because it cannot be found between these two, it is neither existent nor non-existent. Giving is obtained from a cause, so it is not that it previously did not exist and now exists. It does not come from outside, so it does not arise without a cause. Because it perishes, it is not identical, so it is not that this one acts and this one receives. Because of continuity, it is not different, so it is not that this one acts and that one receives. Obtaining the fruit due to the cause, it is not without acting and without receiving. Because 'the seasons and conditions harmonize,' it requires the harmony of multiple conditions to obtain the retribution."