What's the point of jhana?

[serg_o]

What is the purpose of developing jhana in the context of the 8-fold path?
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As a starting point I'd like to observe that samma samadhi is defined in terms of jhana.
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I'll add one more quote:

The Blessed One said: "Develop concentration, monks. A concentrated monk discerns in line with what has come into being. And what does he discern in line with what has come into being? The origination & disappearance of form. The origination & disappearance of feeling... perception... fabrications. The origination & disappearance of consciousness.

Bhagavā etadavoca: Samādhiṃ bhikkhave, bhāvetha. Samāhito bhikkhave, bhikkhu yathābhūtaṃ pajānāti. Kiñca yathābhūtaṃ pajānāti? Rūpassa samudayañca atthagamañca, vedanāya samudayañca atthagamañca, saññāya samudayañca atthagamañca, saṃkhārānaṃ samudayañca atthagamañca, viññāṇassa samudayañca atthagamañca.

http://www.accesstoinsight.org/tipitaka ... .than.html