Why sitting meditation, and is vippasana and breath meditation sufficient?

Question

Why do we have to watch body sensations separately by sitting meditation, when even in our daily life we are experiencing sensations moment to moment (and realizing everything is vibrating in our body)?

And can we achieve omniscience and knowledge of our past lives, karma, etc., by watching breath and watching body sensations only? Or there is more to it in vippasana meditations, other than watching breath and body sensations?

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(This question was originally titled "tibetan buddhism chanting om mani padme hum and watching the breath meditations and watching mental states")

Answer 1

Breath meditation, vipassana and Samadhi meditation are two sides of the coin. Breath meditation is about focused attention that quiets the mind of chatter and noise. It's as if you let a muddy pool settle after stirring it up. Once the mud (chatter) has settled, the water (mind) becomes clear and can now focus more easily and powerfully than before.

Now that's all well and good but what do you do with this focused mind? You point it towards the three marks of existence, and/or the four noble truths. While breath meditation is sufficient as a vehicle to carry you into higher states of concentration (the jhanas) if it is not coupled with insight meditation or some sort of reflection then all you will be doing is building up your concentration faculties without reflection or thought.

There is a section in the Visuddhi margaya that talks about reflecting after exiting the jhanas that is essential to jhanic meditation. I'm at work now but can find the reference later today.

Answer 2

In samadhi meditation, you calm your mind and bring it to a state where you can give commands to the subconscious mind. Then using vipassana you tell your mind (at this stage the mind is clear) the mortality of your life. By doing this your mind will understand the real truth (anitya, dukka and anatama). If you follow the arayan method (arya ashtangika margaya) you can go to enlightenment easily. It consists three stages:

1. Controlling your movements and words (seela)
2. Training your mind (samadhi)
3. Understanding the truth/reality (pragcha)

Each of these stages also consist certain steps, 8 in total.

Answer 3

Why do we have to watch body sensations separately by sitting meditation, when even in our daily life we are experiencing sensations moment to moment (and realizing everything is vibrating in our body)?

Generally what happens is: Body sensation > Perception > Concept formation > Thinking and pondering. Being mindful and aware you do not let this stream lead upto Thinking and Pondering which creates mental fabrication or mental Karma. Being ardently aware is what helps you cut this off before it comes to the last stage of creating Karma. This can also be thought as: Feeling > Craving (for perceived experience - perceive as good, bad or neutral) > Clinging (concepts and thoughts)

And can we achieve omniscience and knowledge of our past lives, karma, etc., by watching breath and watching body sensations only? Or there is more to it in vippasana meditations, other than watching breath and body sensations?

Genrally Vippasana is practiced to gain revolution towards the 5 aggregates. If you develop deep absorptions then yes you can gain insight to past lives and karma. Some Vippassana teachers teach in such away that both concentration and wisdom develops. Interpretations of the Jhanas by Leigh Brasington covers some teachers who teach in such a way, which can lead to absorptions which give psychic abilities (omniscience and knowledge ), as well as, insight.