The river flows. It just does.
It originates from ice, stagnant in its place for centuries before the energy within overcomes the pressure of the surroundings and finally bursts out. Instantly adopting its new nature, it spontaneously seeks out the lowest point to settle.
If you observe, the river is not one. It is but a multitude of individual moments of existence of entities which share the same source but not necessarily the same destination. Tumbling over rocks, gliding over mud, seeping into sand, most of them keep moving, seeking and often even making their own destinies..slowly..very slowly. Some end up as puddles, some make their own rivers, others reach the final destination of the sea.But in truth, most if not all, get to the next form of vapour and get on an even headier journey.
Among those that remain in the flow, some form tumultuous rivulets over rocks, while others silently pool up as puddles and set the stage for paths which are unseen from the main path. These paths don't exist yet. They won't for a century or two. But the droplets need to continue their motions without any concern until there is a new path there.
If distant observers were to interfere with their grand plan for individual droplets, they would be in for a surprise. For every drop they interfere with, there would be scores more that alter their paths to avoid interference and result in something unpredictable. Hell, that could even be the intention of the interference. One can only indulge in the mesmerizing and complex shifting patterns of multitudes of rivulets as they encounter new sieves and obstacles, put there by a distant observer.
Among the many rivulets continuously flowing in their own paths, if one were to pull out a fistful with the intention to changing the nature of the drops, one would find that almost all would pass through. The ones that do come to hand and submit to modification can be let back and tracked downstream. Your interference might stand out if it suits the mighty river, made of individual drops and rivulets fighting for their own paths. It might vanish in a breath if it doesn't blend in. But most often, you would thinking you can see glimpses of your change everywhere whereas the truth would be hard to decipher.