A Discourse on Paticcasamuppada
or The Doctrine of Dependent Origination
Chapter 2 - Rupa And Ayatana
The rebirth consciousness arises on the basis of the heart (hadaya vatthu). The mind ayatana has its basis in the eye, ear, etc. Thought and consciousness too have heart as their physical basis. All the secondary physical phenomena such as the eye, visual object, etc., depend on the four primary elements, viz., pathavi, apo (solidity, motion), etc. The five pasada rupa, i.e. eye, ear, etc., are rooted in the primary elements and their kamma based rupas in jivita (life force) rupa. The five ayatana rupas too depend on nutriment (ahara rupa).
To sum up, citta vinnana is conditioned by at least three mental factors, viz., manasikara, phassa and cetana. Sometimes there arise repeatedly greed, craving, anger, illusion, pride, doubt, restlessness, worry, envy, ill will, anxiety, fear and so forth. All these mental states arise because of unwholesome cetasikas. Similarly, there often occur faith, piety, moral sense, non attachment, compassion, sympathetic joy (mudita), appreciation of the law of kamma, reflection on anicca, dukkha, anatta, and so forth. These mental states arise from wholesome cetasikas. Thus, the yogi realizes the dependence of vinnana on wholesome or unwholesome cetasikas, the eye consciousness on the eye. So it is clear that the manayatana is dependent on nama rupa.
The mind is also vital to the existence of living matter. So the five ayatanas that produce sense organs are dependent on the mind. The sensitive sense organs (pasada) cannot exist without their gross physical bases just as the reflecting mirror cannot exist without the gross matter of glass. So the eye presupposes the gross matter of solidity (pathavi), cohesion (apo), heat (tejo) and tenseness (vayo); in short, the ability to see depends on the gross physical body of the eye. The same may be said of the ability to hear, the ability to smell, etc. Further, we can maintain life uninterrupted only because of life force (jivita rupa) and nutriment. All these facts show how the five ayatana rupas originate with nama rupa.
The sixth ayatana viz., manayatana comprising thought, reflection, intention, etc., depends on wholesome or unwholesome mental states such as greed, faith and mental factors such as phassa (contact) as well as on its physical bases. It arises from its root viz., bhavanga which in turn forms the basis for the mind process (manodvara vithi).