This fountain is found in a prominent public place. It has two flows of water, side by side, fed separately from a single transparent tank at the top. A pipe between them pumps the water back up to the tank.
Imagine the waterfalls however you like, as the design is open to tender. Perhaps the water
will trickle or cascade down some slopes. It would be good if it makes some wheels spin as it flows down, like Tibetan prayer wheels. Maybe one side is brightly-lit with rainbows of light sparkling through the water, while the other side is blues and greys and darkness.
The flow of water is controlled by data received on a website. The website invites members of the public to think about their actions over the past 24 hours. For as many actions as they want, they click to locate the action on a grid. The x axis is timescale (updated according to the current time) from 24 hours ago to now. The y axis is how good or bad they feel their action was. From world-savingly good, to pet-pettingly good, to spitting-on-pavement bad, right down to killing-Father-Christmas bad.
While it's left open to the individuals themselves to choose how to decide on the goodness of their actions (Intuition? Virtue ethics? Utilitarianism? Religious morality?), self-honesty is encouraged, and 'leaving out the bad stuff' is discouraged. Of course, no-one except yourself knows what you selected and why.
All the clicks are scored according to the level of goodness or badness selected and the total score for all users for each minute is tracked. At 10:07am on Wednesday, the amount of water that flows down each side of the fountain corresponds to how good or bad people admit to having been at 10:07am on Tuesday. Perhaps on the 'good' side, two drips fall out, while on the 'bad' side, a whoosh of water flows guiltily forth? Hopefully not... but that's up to you, the people, to decide.
(Alternatively: people admit to how good or bad they've been that day in general - one click per person rather than per action - and the fountain flow is adjusted in realtime. This was my original idea, but might need some fiddling since most people will log on at certain times of day... though that would be fine for a world version.)
People passing the fountain will thus be able to see the moral state of the nation. This might instill hope, evoke sadness, create anger, cause boredom, or stir up other emotions, depending on flow rates and personal attitude.
As a bonus, you can track your own and the overall statistics on the website (anonymous log-in required), seeing what patterns there are to when and when people are good or bad... and whether your own scores are increasing or decreasing over time.
Possibly, the waterfall could also be therapeutic for people: seeing their own bad actions as a trickle in the stream might help them move past simply feeling guilty stage into genuinely resolving and taking action to do better next time.
The transparent tank at the top is symbolic of the potential within people to choose which path they want to follow, neither doomed or destined to be good or bad, the pool at the bottom of the fountain reminds us that 'good' and 'bad' are value judgments we label reality with (for good or bad), and the waterfall itself helps steer us away from excessive pride, as it reminds us of the transience of our actions, mere droplets in the stream of life.