Deep thinking used to bring answers, enlightenment, knowledge of the living universe. Those who were loners, often alone, found much in those places of thought and it took a while for those who weren't loners to find alone time to 'ruminate' beyond a certain point, but they were pushed by those loners.
Saruman: "The Dwarves delved too greedily and too deep. You know what they awoke in the darkness of Khazad-dûm: Shadow and Flame!"
There came a time when they weren't impressed by the thoughts of invention that peppered their minds here and there, weren't impressed with the romance, the love, the valleys and mountains, forests and oceans, deserts, etc. When they were no longer impressed looking at the great cities of the mind or creating their own there and weren't content at the pace that nature told them they would need to move at as a species, together, to reach those cities, and that those living would not be alive then. They pressed the universe, forced themselves upon and through reality; did indeed delve too deep and greedily and became the enemies of reality as they wove together and refined and defined the spells and magics of manipulations, fire and ice and dust and wind; the wild and the tame; worked to control illness and health, life and death and they awoke in those deep places a nameless dread, a fierce and fiery anger that was darker than they every knew. Early races worked together to build a tower to the heavens to escape the Hell in the land; that tower was called 'Babel', or 'babble', as in the great cacophony of chaotic voices chanting, making no sense, but like a river winding and bubbling; every chattering. They found no solace in their tower, for near to completion, it towered above the land, high above it where the air began to grow thin and still they pushed onward and upward, creating a singular language for them all to share; a common-speak to bypass the barriers of their own learning and growth, for they had been brought together, heightened by power and energy to become Gods of their time and still seeking to displace the God on most-high. The barrier that divides us from space, our atmosphere, combined with the coincidence of so many other things, smacked them down; destroyed their tower in a great thundering as lightning split the sky and it slowly crumbled into dust over the ages as they were scattered and so 'Babel'; 'Babble', split them again. In their fear and deep shock, they retreated deep within their own races, their own groups, retreated deep and left the barriers up, for now they feared without more than within and hastily; in their fear; rushed back into the depths of the mind and spirit, divided by language, distrust; and bound together by mutual secrets and fears.
Unto this modern age where again they began to fear the depths of thought, began to soar outwardly without fear and began to learn the secrets of a universe now much wiser and less trusting.
But still, they are afraid, these humans and, not just humans, but everything. No longer do we build towers to the heavens; no longer do we build cities over oceans and lakes to prove we are mightier than nature. Such marvels as a city on water exists, but not to prove that we are mightier than nature, but to exercise artistic license. We no longer seek to match nature with its intricate beauty; even our most stunning achievement, a system of checks and balances used by the US is but pale imitation and in far limited degree to our own reality and it is staggering beyond belief and not anything that we could have come up with on our own. They say that the Egyptians could not have created the pyramids on their own and I said why not? They said that the Egyptians would have had to use pulleys and ropes and that that was beyond their level of civilization and yet they also had irrigation, which was supposed to have been beyond them, but even without ropes and pulleys, it was deemed to be impossible to move those big blocks and they forget so easily the whips at our backs, the sheer necessity to get done and the shining leaders of those people, Ramses the damned most noted among them. They worked out in that blazing sun for their God, Ra; they bent their backs under the whips, sweated their rust, those golems of flesh and blood and they pushed beyond the boundaries of the flesh. It is right they couldn't have done it without help, but it wasn't necessarily aliens, though it could have been, to dip into conspiracy theorism, but just the same; an excess of spirit does incredible things, grants extreme power to a mite, where a toddler can swim a mile out to save a parent and a mile back without being tired; a man or woman filled with an 'adrenaline rush' can flip a car over on their own. Just the same, humanity quite brazenly did design its own societies, and yet there is ever the circumstantial evidence that we are not alone, all around us, supporting our faiths, our mysteries, our beliefs in things beyond what we can see, hear, taste, touch with our physical senses. The energy that fills and consumes, the thoughts that flit, and the flesh that is either willing or unwilling or indecisive.
But, rumination began a long time ago for many reasons. It began from many sources, not just one and came together throughout the ages as mankind brought itself up from the primordial soup we claim to have climbed out of and yet dinosaurs existed before us, they came first and then evolved down into the animals we have now. Mankind did not crawl out of that soup; it did not even crawl out of the ocean as those evolution posts show, and might not have passed through just monkeys and apes to stand upright, might have passed through worms, birds, dogs, cats; etc. Rumination, deep-thinking, the causes behind it have technically always existed and yet each being; each entity; each person; comes into deep-thinking and rumination for their own reasons, even if those reasons are repeats of what's already been done and each one does it in their own unique way no matter how similar it might appear and does this not strike you as being perfectly reasonable if you push all barriers to the side and actually believe in mental and spiritual time travel, believe that thoughts of invention have been passed to the past, or side-to-side, or from a distance; that creations have never been just the creation of the beings and entities that have pushed them out, that they flowed through, but the children of so many beings and entities, culminating in the breach that causes them to be pushed out into 'creation'? Therefore it stands that rumination has always been the search for answers and when those answers no longer soothed, the pushing to create again, create anew; to redefine and refine and then of course, to safeguard and protect or forbid and ensure nobody can make use of the knowledge again for it can only be used for 'evil', or so the original thinkers dared claim and state and perhaps they lived, some of them, in our age of the world, our eon and epoch of time and space; perhaps in others and yet still just on the same level, proving for all the world that we have not evolved at all and only have gone in circles, while the evolution that we know of as evolution is only adaptation and pushing to become what we know already that we can become, mixed in with the self-same traps of the minds and spirits of what's possible in spirit realities and what might be possible in reality.
Is it any wonder we now live in an age where people don't allow themselves to think and don't allow others, say that we think too much or think too deeply, make fun of us, dog us for it, that people would rather push outward out of themselves than to go inward where the thoughts lay in a reasoning engine long left to gather dust only to have come back to life much to the dismay of them all, kicking up demons and spirits long considered dead and gone, or broken; all to fight a new fight in the modern age against 'fifth dimension' mechanics of complexity and complication with 'third dimension' physicality and insight.
If you want the full history of rumination, you must go to the future, too; to the sides, to note that time does not flow just in linear fashion, though it is always linear, no matter how it travels; to itself at the least. To the underlayers and overlayers of reality, to the alternates and to their futures and their pasts and to each individual and the differences there in perception and perspective. If you want truth at all, then there are paths you tread as you search for truth, though truly you will not understand it or grasp it fully until the search for truth finally leaves you and you no longer care, because your search becomes a search for power, knowledge; rushed through; of wisdom without wisdom. All of this was came up with in the moment without prethought, without rumination on my part. Just, in the moment, have never given some of these thoughts much thought at all and see them as they flow through me, the conduit for them to grace this conversation. They came from many sources all in one moment to come together into this post; this reply. Is that not evidence enough of some of the things said here, at the least? It should be. Evidence of some truth, some power, some... thing... beyond what we care to establish as fact for the 'mindless' masses that kindly flip us off and tell us to kiss their asses.