How does one "practice Buddhism"?

Intro

To an outsider, "Buddhism" appears to be (more or less) one monolithic tradition. You sit, you meditate, you attain nirvana. Maybe practitioners in different countries (or even adjacent monasteries in the same country) wear different colored clothes or hats, but that's basically it.

After years in search of what constitutes Buddhist practice, I find I'm far less sure than when I started. No doubt many (probably nearly all) practitioners will vehemently disagree with what I'm about to write below, but there seems to be mounting evidence that the sub-schools heartily disagree with each other, and none seems to be truly "authentic."

I've done no original research here; I'm just sharing some resources and what I've learned from them. We'll focus on three rough schools of Buddhism: Theravada, Zen, and Tibetan Buddhism.


1. There is no agreed upon definition of jhana, or technique to attain it

http://leighb.com/Jhana_in_Theravada_Quli.pdf

This paper explains how the details of the most fundamental meditative states emphasized by the Buddha (the jhanas) are not remotely agreed upon even amongst Theravadins. To what level must they be developed? Are they necessary for enlightenment? No two (sub-sub-)traditions seem to agree.


2. There is no one agreed upon meditation technique even within Theravada

http://meaningness.wordpress.com/2011/07/07/theravada-reinvents-meditation/

In the above post, the author describes how Theravada (the school most often considered to be aligned with the words of the historical Buddha) actually has no lineages of practice that can be traced back before about 1900.

Vipassana was reinvented by four people in the late 1800s and early 1900s. They started with descriptions of meditation in scripture. Those were vague and contradictory, so the inventors tried out different things that seemed like they might be what the texts were talking about, to see if they worked. They each came up with different methods.

Since then, extensive innovation in Theravada meditation has continued. Advocates of different methods disagree, often harshly, about which is correct.

3. The (one) man who brought Buddhism from India to China, which later spread to Japan, which became "Zen", may never even have existed

http://en.wikipedia.org/wiki/Bodhidharma

Several scholars have suggested that the composed image of Bodhidharma depended on the combination of supposed historical information on various historical figures over several centuries.[68] Bodhidharma as a historical person may even never have actually existed.

4. The "pinnacle" of Tibetan Buddhism, Dzogchen, was introduced some time after 55 CE, by a man born in modern-day Pakistan, who it is freely admitted has no (earthly) connection to the historical Buddha

It is held that he received the teaching from a celestial Buddha, of whom the historical Buddha was a manifestation. Not only that, but the same teaching seems to have existed in the aboriginal religion of Tibet. They claim that it was first taught by a man who predates the Buddha.


5. No two traditions seem to agree on the endpoint of practice

In Theravada, it is traditionally held that one practices to become an arahant. In Zen, one aims to become a Buddha via the bodhisattva path. Meanwhile in Dzogchen, they claim that only Dzogchen practitioners attain the ultimate realization called the rainbow body.

We don't need no stinkin' witness

After some experience meditating, it's easy to come to the conclusion that "I am not my thoughts." The more closely one observes one's experience, the more one sees that one is indeed not any of his perceptions, but is merely witness to them. Thoughts come, thoughts go, perceptions come, perceptions go, and "I" stand alone as observer of them all.

But it's easy to get stuck at this realization, and feel there's no more left to discover. Can we go deeper?

Imagine looking at a dog. Now notice that you are not looking at a dog, but more precisely at the image of a dog. For example, in a dream you could have exactly the same visual experience, but there's no dog there.

More generally, one does not experience things, but perceptions of things.

Now, what does it mean for something to be a perception? Would it still deserve that title if it were not being perceived? Was that image of a dog just waiting somewhere for you to perceive it, or was it an "image" only while it was being perceived? Investigate this question very closely in your experience, and resolve that a perception that is not being perceived isn't a perception at all -- it's just the thought of that perception.

Perhaps you can feel the steel jaws of logic getting their grip.

Every "perception" already contains "the perceiving" of it. It is a self-contained unit, and has no need for some "perceiver" to come along and perform some more perceiving. There's no job left for such a perceiver to do.

At best, one could say that there's a subjective aspect to experience, which we sometimes conceptualize as a separate "witness." But like all other conceptualization, it doesn't quite touch the deep truth of things, it seems.

Mistakes

The typical mistake made by a non-practitioner is to believe that experience can be permanently improved (i.e., that I can become happier) by rearranging bits of experience (i.e., doing stuff).

The mistake commonly made by practitioners is more subtle: it's that we can somehow improve experience (get more enlightened) by doing something (possibly very subtle) with our minds. There can be this underlying sense of improving our minds in some way. To make them calmer, clearer, sharper, etc.

But how would you do such a thing? Where is this mind you seek to improve, anyway? What properties does it have that could be improved upon?

This is why Mahamudra instructions spend a lot of time making you search for the mind and its characteristics.

Dzogchen instructor James Low comments (on a Dzogchen teaching from a master):

The purpose of this teaching is to give you confidence to trust that the mind is pure from the beginning. You cannot purify that which is already pure so don't waste time in that direction. ... The more you see there is nothing for you to do the more you find yourself relaxing.

And, after all (Thrangu R):

A relaxed mind is all that is necessary. Perfect meditation will arise in a perfectly relaxed mind. 

Tulku Urgyen R:

The antidote for exhaustion is, from the very beginning, to relax deeply from within, to totally let be. The best relaxation brings the best meditation.

We need the best relaxation. The difficulty comes from not having this. What becomes tired is the dualistic mind. 

And finally:

Our body is the Bodhi tree,
And our mind a mirror bright,
Carefully we wipe them hour by hour,
And let no dust alight.

That is the poem that was refuted by Hui Neng, who went on to become the 6th Zen Patriarch, with this gem:

There is no Bodhi tree,
Nor stand of a mirror bright.
Since all is void,
Where can dust alight?