[2158] A phenomenon (dhamma) with an external object (bahiddhārammaṇa) is a condition for a phenomenon with an internal object (ajjhattārammaṇa) by decisive-support condition (upanissaya-paccaya): object decisive-support (ārammaṇūpanissaya), proximity decisive-support (anantarūpanissaya), natural decisive-support (pakatūpanissaya).
Natural decisive-support: contemplation of impermanence (aniccānupassanā), contemplation of suffering (dukkhānupassanā), and contemplation of non-self (anattānupassanā) with an external object are a condition for contemplation of impermanence, contemplation of suffering, and contemplation of non-self with an internal object by decisive-support condition.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.