Undoubtedly this question or some variation has been posed before, since I cannot imagine that my experience is unique, but I've looked for it and haven't found it. I apologize for the redundancy.

To begin with a hopefully comprehensive caveat, this isn't an attempt to figure out what is "right" or "wrong," but comes from my desire to understand which is right or wrong for me. Any time you put two systems up beside each other, though, they're usually perceived as being against each other. On the contrary, I'm willing to accept that the Buddha taught quite a few paths, each depending on the mind of the student. However, ecumenism only gets you so far in personal practice - there are some points I would like clarification on before I really decide on my own practice.

So I hold my breath and ask: How does the Zen taught here compare to the Buddhism taught in the Pali canon? I started formulating this question when I came across a quote:

"And what, monks, is right effort? There is the case where a monk generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the non-arising of evil, unskillful qualities that have not yet arisen. He generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the abandonment of evil, unskillful qualities that have arisen. He generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the arising of skillful qualities that have not yet arisen. He generates desire, endeavors, activates persistence, upholds & exerts his intent for the maintenance, non-confusion, increase, plenitude, development, & culmination of skillful qualities that have arisen: This, monks, is called right effort."
This is a very active attempt at modifying the contents of mind. This isn't the only such quote, of course. There's also the discussion of distracting thoughts in MN 20, in which the Buddha goes so far as curb-stomping distracting thoughts. There are quite a few places in which the good bhikkhu is to track down the bad parts of himself with a machine gun.

Obviously this is not the case in all schools of Buddhist thought and maybe even anathema in Zen ("unwholesome?! desire to be different?!" *whack*). At first I understood the difference as one of emphasis and technique. Ajahn Brahm explained it as giving a wild bull a whole field to run around in, thereby calming it down over time, or lashing it down with ropes, quickly teaching it that it would have to behave. However, the more I read in both the Pali canon and Zen literature, it seems they have little tolerance for the other's technique. There is, of course, the famous poem:

Fundamentally no wisdom-tree exists,
Nor the stand of a mirror bright.
Since all is empty from the beginning,
Where can the dust alight?
I hope I can let that one speak for itself, especially in opposition to the other monk's poem. I've read in quite a few places that attempts at modification aren't Buddhism or won't work, and yet that's all over the Buddha's own words.

To rephrase the question, then, how is it that shikantaza accomplishes the same things, when it seems perfectly willing to let persist as long as they like the things the Buddha recommended we beat down? What is the connection between sitting and the whole body of the dharma in daily life? I understand the quotes that just sitting is the perfect fulfillment of the way itself, but that doesn't ring true from where I sit. Again, I'm not trying to imply that Zen isn't Buddhism or that shikantaza is wrong, but I do fail to see the connection between progress on the path of mental purification and just sitting, especially given the seemingly shared antagonism from each school of thought towards the other. How is Zen Zen Buddhism and how is it the Dharma?

Again, I pray this doesn't devolve in the way it usually does. Please understand that I'm asking this for personal reasons, not to tear down the entire edifice of Zen.

With a grimacing gassho,
Dusty