A knowledge of the future - even couched only in possibilities and probabilities - is (despite its dangers) a rare and precious gift for which some would risk everything.
Although there is some scant evidence of possible precursors and earlier iterations, the most famous example of a Janus Tree (from which example the phenomenon came to inherit a title) was discovered near Rome in the years following its founding. Found deep within a dense forest, almost obscured by the heavy shadows cast by the canopy of branches and leaves, its size and unnatural appearance was still enough to draw attention. Boughs and bark gnarled, knotted into patterns that looked - to the constantly questing eyes of men - like human faces twisted into frozen anguish, in an age already rife with prophecy and prognostication, where augurs and oracles were often employed in an official capacity, the people could not help but be compelled to further study and investigate such a naked and unabashed omen.
The tree was named for Janus, the god of doorways and duality, of time and transitions and of beginnings and endings, whose two faces were said to look back into the past and forward into the future. Distinct from the other trees around it, but obviously more a mutation than a separate species, the seers and soothsayers of Rome immediately recognised it as having religious significance but quickly fell into disagreements about how to incorporate it into ritual practice. Leaves, cuttings and samples of sap were taken - the intention being to variously imbibe, ingest or to inhale them - in the hopes of unlocking some divine missive or instruction on how to interpret the tree’s existence. These measures met with unalloyed failure: The Janus Tree was gnostically inert, a code with no apparent cypher.
Over the next decade, and as efforts to discover the reason it had grown there (and thusly) dwindled, the tree’s significance diminished. It came to be seen just as a shrine, albeit an uncommon one, and fewer and fewer made even the short pilgrimage there as other markers and temples - dedicated both to Janus and, more broadly, to the pantheon of which he was a part - were built. A handful of worshippers remained dedicated nonetheless, praying and holding frequent vigils in the forest. They were certain that there was some hallowed promise to uncover; an assumption that was (literally, at least) almost exactly wrong. It was the night before the eve of a new year when someone fell asleep amidst the roots of the Janus Tree; roots which encircled and bound them tight.
Hidden and half-buried, the man’s absence was noticed but not remarkable until, two days later, the roots loosened and he was able to claw his way free. Discovered in a state of shock, weakened by hunger and dehydration after his ordeal, at first only a little of what he was saying (and he seemed to have a lot to say) appeared to make sense. It was almost a week before he could properly organise his thoughts, before he could articulate his experiences and what he had unwittingly discovered. The tree imparted something of Janus’ vision - his ability to look ahead with as much clarity and certainty as he looked back - and had returned the man with a renewed understanding of his past year, but also with unlived memories of the one to come.
The knowledge - sometimes styled ‘precollection’ (a somewhat artless antonym to ‘recollection’) - had the same weaknesses and failings as memories that were formed more typically: Recent, significant or personally momentous events were remembered keenly, while the distant and the humdrum faded into vague, often-incorrect impressions. Despite being a limited and solipsistic form of precognition, it still represented a deliberate and direct link to the divine, and the potential of such an experience made it highly-coveted. Encouraged and supported by the ever-growing city and state of Rome, the worshippers attempted to recreate and replicate the conditions of the incident. They eventually went so far as to try burying people alive beneath the Janus Tree, dragging and draping the roots about them. Only a few survived, none of whom received any sort of blessing or benediction.
It is unclear who worked out that the timing of the first event had been vital, that the tree could only take people for the last day of the passing year through to the first day of the next, but when the next opportunity came there was almost a score of people waiting for their chance. The Janus Tree took them all and, for two days, the ground rose and fell with their slow and shallow breaths. Three of their number - too weak for the exertion - passed on before the roots released them, and the rest, still recovering from the anticipated ordeal, saw that the tree was also beginning to die. Wilting and fragile, branches drooped and snapped under their own weight while unseasonably dried-out bark split and peeled from the thick trunk.
Within a few weeks, and despite careful attention, it had collapsed under its own weight and withered away almost entirely from desiccation and dry rot. The tree was gone, used up and passed into legend, and it would be over two-hundred years before another was found. Though of quite a different species to the original, and discovered on what would come to be known as the Orkney Islands (over thirteen hundred miles removed from its predecessor’s forest), it was warped in a similarly striking fashion. The myth of Janus was dim and distant - and that of his tree even more so - but the same cycle of discovery ultimately played out again. Between the limits of the miracle, and people’s eagerness to exploit it, this new Janus Tree was drained and depleted soon thereafter.
This pattern has repeated over and over ever since, all across the world and with dozens of types of local trees bearing the same gifts. There is some contention as to whether these trees developed naturally - their eventual gifts inherent before the seeds from which they grew first budded - or if they were chosen later; warped into their more recognisable forms by an outside force. Certainly, there is no evidence that a Janus Tree has ever been discovered whilst still a sapling, or even any tree that appears to be less than centuries old. Some have even hazarded, given that there has never been more than one Janus Tree at any time, that they are inhabited by Janus (or some other, sympathetically-empowered entity). Not shrines then, but the last refuges of a god.
Despite the potential enormity of what the Janus Trees can offer, especially to those who have been careful - or selfish - enough to keep their discovery a secret and prolong the number of years it could grant its favour, there is little to suggest that the overarching course of history has been dramatically altered by those with the benefits of such foresight. Few Janus Trees are known to have come to the attentions of those with much personal or political power, and those with aspirations to the same only have a limited window to exercise their advantages. Still, as their legend has spread, competition to discover and possess them has increased: Many fortunes have been squandered by those who believed their investments would be recouped a hundredfold once they could see their own futures.