ADN

Well, I know I can break human will if given enough time, incentive, and history to thrash your mind into a pulp of concession. To put it simply, "the hole", or just a small confined dank and dark space that relinquishes you of all your senses, can and historically will, hamper the spirits of many more men than any other form of will-altering performances. Then, after which, you can re-teach the person from the ground up what is what, and what will be expected of them.

I don't know if I can say the same thing for natural forces on Earth, such as water torrents, or temperature.
Not sure if you can "break" or alter water, other than by atomically pulling apart the hydrogen and oxygen molecules, or alternatively, by simply building an efficient dam to ease the flow.

I think it is much easier to mold a mind than it is to recreate nature, is what I'm saying, especially if I am working on both projects on my own with only the skills and technology I possess at this moment. If I had one those specific 120-ton destruction tractors, sure, I could make a new canyon, but all I would need to "effectively" infilitrate one's mind is an insulated empty closet, a fair assessment of who the person is, their family, their goals, and maybe a radio speaker. Oh, and two-three weeks of isolation. Then, we'll see where it goes from there. :D

I do see why the human spirit could be thought of as strong and enduring, but I'd also like to state the case of why, how, and under which circumstance it can become fragile, weak, and utterly useless. Human spirit works best when en masse, focused and deliberate, and with a strong foundation of an audience. Otherwise, the human spirit can be quite aimless and singular, selfish even.

Yeah what I was going for was potential strength and power if used and harnessed properly to the full extent that it can..... not really an on average or when viewed with how weak it can be as well.

I just took the question to not mean consistently or while observing how easy it can be to shape and mold, because I agree with you, if we were looking at it through that frame....we may have to turn away from esoteric answers and focus primarily on natural forces. And I would also have to agree with you that if we look just at the four generic ones, earth, wind, fire, and water....water would seem to be the most powerful of them all.

Untapped forces, well, then yeah, human will would, arguably, be the best and highest form of power.

The same with magnetism, as I posed earlier, and electromagnetism's cousin, the abundant and always-present gravity. In terms of small-scale, it is both weak, yet has the potential to be incredibly strong. At the grand scale, say the size of the entire planet, again, it can still be seen as a generally weak force, but also, in that it affects every region, area, and corner of the Earth, one can pose the contention that magnetism "rules" us all.

Just because that Cot-damned history Channel ran that ridiculous "2012" campaign on scaring the shit out of every curious American again this weekend, I'm gonna mention this: we may yet see why universal magnetic repulsions are a true reckoning force, as the moon's gravity controls our tides, Earth's gravity controls our space, direction and awareness, and the Sun's gravity controls our very existence and the nature in which we are actually able to be "alive" at this point in time and in this precise "habitable" spot for the fostering of life. So, well... if there is to be cosmic alignment, and if the magnetic poles shift suddenly on our planet, I have absolutely no idea how and to what extent this can adversely affect us. I just know at the worst, it's gonna suck, as in "total nonexistence" kind of suck.