The Long Āgama Sūtra 14.33-34

14.33

佛告帝釋：「愛由想生，因想緣想，想為原首，從此而有，無此而無。」

The Buddha told Śakra: 'Desire arises from conception. Caused by conception, conditioned by conception, conception is its origin. From this it exists; without this, it does not exist.'

“But I don’t understand the arising of conception. What is its cause and condition? What it its source? From what does it come to exist? From what does it cease to exist?”

14.34

爾時，帝釋白佛言：「實爾！世尊！愛由想生，因想緣想，想為原首，從此而有，無此則無。我今聞佛所說，無復疑也。但不解想復何由而生？何因何緣？誰為原首？從誰而有？從誰而無？」

At that time, Śakra addressed the Buddha, saying: 'It is truly so, Bhagavat! Desire arises from conception; caused by conception, conditioned by conception, conception is its origin; from this it exists, without this it does not exist. Having now heard what the Buddha has spoken, I no longer have any doubt. Yet I do not understand: from what does conception further arise? What is its cause, what is its condition? What is its origin? From what does it exist, and from the absence of what does it not exist?'