Dhamma Vibhaja Vietnamese Group Q&A 4 November 2023 (37:00-38:43)
Yogi: I notice that breathing in and the rising of the abdomen happen at the same time.
Sayadaw: Everybody thinks that cause is first and effect follows. In Buddhism, sometimes cause happens first and effect is later; and sometimes both cause and effect happen simultaneously.
When we switch on the light and light appears, which comes first? Right? This is cause and this is effect, but they happen at the same time.
It is the same with the breath and the movement of the abdomen. There is already some air in the lungs; so, when you breathe in, both the in-breath and the rising of the abdomen happen simultaneously.
If you can be aware of two objects at the same time, then you can be sure of the answer.