tiṣṭhaty ā pākakālāc cet karma tan nityatām iyāt |
niruddhaṃ cen niruddhaṃ sat kiṃ phalaṃ janayiṣyati ||
If an action persists till the time of ripening, that would be permanence.
If it has ceased, then being ceased, what fruit will be produced?
This verse from Nāgārjuna's Mulamadhyamaka-Kārikā (MMK 17.6) is important because it shows that the standard versions of pratītyasamutpāda and karma are mutually contradictory. Pratītyasamutpāda says the conditioned cannot persist after the condition has ceased (asya nirodhād idam nirudhyate) while karma requires the conditioned arise long after the condition has ceased. This problem, which I call Action at a Temporal Distance, drives a good deal of innovation the Abhidharma period and after as Buddhists realise the problem exists and try to invent ways around it. For some descriptions of this problem and the proposed solutions, see my collection of essays on karma and rebirth.