In a moment of irony during Indian Prime Minister Narendra Modi's visit to Japan, an official in the beautiful city of Kyoto told Mr Modi that the Japanese had learnt their habits of cleanliness from the Buddha who, of course, was born in India.
Mr Modi listened, then murmured: "But we in India have forgotten all this."
Amid the unusual bonhomie that has marked this visit, Mr Modi has persuaded the Japanese, among other things, to help clean up the River Ganges and the sacred Hindu city of Varanasi through which the river flows.
Let's hope the Japanese know what they have let themselves in for. Cleaning Varanasi and the Ganges is a promise that Mr Modi made days after being sworn in, partly because, in the May general election, he stood for election in Varanasi where he won by a handsome majority. But if Mr Modi and the Japanese are to succeed, it will mean changing the daily habits of Indians. On this, Mr Modi has made a start by telling Indians some home truths.
For the first time in decades, a prime minister is telling Indians bluntly that India is dirty, its cities and towns are scenes of unbelievable squalor and filth and it is all because many Indians have dirty habits.
It's not a nice thing for him to have to say, or for Indians to hear, but it must be said if anything is to change. India's villages are pretty grubby but they are nothing as compared with urban filth.
People throw their rubbish out onto the street without caring who will remove it; as long as it's out of their house, it's fine. Men urinate everywhere and spit. Families litter without a thought. Cleaning up is always somebody else's responsibility.
A recent visit to Varanasi confirmed that living in dirty surroundings seems to have become normal in India. This city is sacred for all Hindus but they don't mind if its special status is sullied by dirt. Experts estimate that 3,000 million litres of untreated sewage are pumped into the river every day.
It's the same all over India. Releasing a report earlier this year, Vice-President Hamid Ansari said: "Indian cities produce nearly 40,000 million litres of sewage per day... and barely 20 per cent of this is treated." The untreated waste seeps into rivers, lakes and ponds, contaminating the country's water sources and turning them into, as Mr Ansari said, a "ticking health bomb".
Yet, many Indians seem blind to the dirt around them. I saw families in Varanasi happily eating their roadside snacks right next to open sewers infested with flies and on streets dotted with animal excreta.
Maybe Mr Modi caught a glimpse of the Varanasi filth during his campaigning in the city because one of the first things he said on returning to the city was to say it needed to be cleaned up.
In fact, he keeps talking about cleanliness. The last person who used to talk so much about this was Mahatma Gandhi, who used to make a point of cleaning his own toilet, a habit which Indians prefer to leave to others.
Mr Modi even used the loftiest date on the calendar - Independence Day - to talk about dirt and how shameful it was that half the population still defecates in the open. On one occasion, he ordered civil servants to clean and tidy up their offices and clear away the clutter. Huge vans were seen leaving government offices, full of yellowing files, documents and rusty equipment which had been lying around for years.
On another day, he urged Indians to make India clean as a tribute to Gandhi by 2019, the year they will celebrate the 150th anniversary of his birth.
But it's not enough to say India must become clean. Mr Modi knows he has to tell Indians: You are the ones who must clean India up. This is a crucial point because the ingrained tendency, born of some notion of the state as a paternalistic force, is to expect the government to do everything.
When I ask the shopkeepers in my neighbourhood market why they don't get together to keep the area clean of litter, stray dogs, rubbish, broken paving and stagnant water, they say it's up to the municipal authorities to do this. Few think of pooling resources and combining forces to clean up around them.
Mr Modi's focus on the basics is a bit distressing on one level - do adults really need to be told to keep their surroundings clean? - but welcome on another because India needs to dump its fantasies about superpowerdom and concentrate on basic facilities.
That is why Mr Modi's promise to build a toilet in every government school is sensible. Lack of access to toilets causes girls between 12 and 18 to miss around five days of school every month during their menstrual periods.
Unicef estimates that 400,000 children under five years of age die each year due to diarrhoea. "With 594 million people defecating in the open and 44 per cent of mothers disposing of their children's faeces in the open, there is a very high risk of microbial contamination (bacteria, viruses, amoeba) of water which causes diarrhoea in children," the organisation says.
If Mr Modi can clean up this country and give Indians the civic sense they once presumably had, he will be doing a greater service than any adding of percentage points to the gross domestic product.
The writer, a former BBC journalist, is a freelance journalist based in New Delhi.