It's fair to say that geologist James Hutton (1726-1797) was a rock star of the Edinburgh Enlightenment. He knew about rock and he knew about unconformity (geologically speaking) and offered what was, in his time, a revolutionary way of seeing the world.
By studying rock formations that appeared adjoined, but totally different in origin and age, he was able to show people that their planet was much older than they had possibly imagined.
Hutton compiled his 25 years of geological studies, much of it done in the Edinburgh and Scottish Borders area, into his seminal "Theory of the Earth" paper which he presented to the newly established Royal Society in Edinburgh in 1785.
And so the geological concept of "Deep Time", of a world that is billions of years old, was born.
Hutton's ideas were mind-blowing at the time.
"The mind seemed to grow giddy looking so far back into the abyss of time," is how his friend, eminent architect William Playfair described listening to the geologist's ideas.
"Deep Time" also made a great starting point for last night's Edinburgh International Festival Opening Event, a free rock 'n' roll light show by 59 Productions projected onto Edinburgh Castle and the castle rock, set to a soundtrack by Glasgow band Mogwai.
After opening the festival last year with The Harmonium Project, a light show on the exterior of the Usher Hall also by 59 Productions, expectations were high for Deep Time. There was sponsorship in place - Standard Life - and even a Facebook live stream of the 20-minute show planned for the night.
Of course, this being Scotland, there were unseasonable storms. In the morning, the Foodies Festival had to cancel the last of its 3-day event for safety reasons and there were concerns about whether Deep Time would be affected too.
"It's a bit rainy, but that's just fine! Just leave your umbrellas at home please," came the reply from the Festival PR over Twitter.
A crowd of around 30,000 people were regaled with a mesmerizing, almost hallucinogenic display of movement and colour spread out across the broad canvas of Edinburgh Castle's western facade. Unfortunately, for those trying to watch on Facebook, the livestream never was. An HD video recording was posted on Facebook a few hours after the event and on YouTube in HD.
Clocks are a recurring theme in the show, from start to finish: clicking, ticking, spinning, and even floating like amoeba at one section where pre-historic skeletons stretch across the ramparts.
Rocks, too, naturally feature throughout. Bubbling lava is splattered across the ramparts reflecting Edinburgh Castle's volcanic history. You can see that the show's creators are having fun playing tricks with the audience's expectations. At one point, the castle rock appears to collapse in a cascade of tumbling boulders. Such is the precision of the projections that the distinction between the real world and created images is constantly blurred.
At one point, a smaller version of the castle appears projected onto the castle. This castle within the castle is then lifted up, expanded and overlaid directly over the castle itself so they become one seamless thing. Amazing.
The transitions from one scene to another are so smooth, with such variety of textures and shape to the imagery, that even the (real) trees bouncing around in the strong winds seem in keeping with the energy of the show.
Deep Time doesn't have a strong unifying narrative, more of an overarching theme of life's transience in the grand scheme of things, expressed with an abundance of style and symbolism.
It's effective. Keeps you guessing. Those gharish, technicolour stripes lighting up the castle rock at the end - are they a reference to Hutton's Unconformity?
The atmosphere of the show is greatly enhanced by the cinematic quality of Mogwai's heavy bass, electronic soundscape.
Among the quotations scrawled in large on the castle rock at various points in the display, is the famous lines from Macbeth: "Life's but a walking shadow, A poor player. That struts and frets his hour upon the stage. And then is heard no more." In the context, as planet Earth morphs before your eyes, there's something comforting (and prescient?) rather than hopeless in Macbeth's words.
Our lives are short. Terribly short in geological time. We can't even imagine.
As Hutton says: "We find no vestige of a beginning, no prospect of an end."
What the show has is a certain bravado and fun in the face of the hopeless, temporal enormity. Like the image of the castle, Time can be conceptualised, and folded up into a 20-minute show, peppered with local references and even with hundreds of photos of Festival friends thrown into the mix.
Here's the Big Bang, it seems to be saying, enjoy it! And - as a map of the world is projected on the castle with an arrow pointing to Edinburgh - enjoy what's happening right here, right now.
Deep Time took place on 7th August. To get the most out of the video, darken the room, turn up the speakers and watch on a big screen.