Mary Kenny: 'Young girls with courage have long been mocked, but Greta is an inspiration to all of us'

St Joan of Arc was a primary example: the peasant girl who, aged 17, heard supernatural voices telling her to put some backbone into the weak king of France, then led an army herself to rout the English. St Bernadette of Lourdes, similarly, was just a young teenager whose vision was mocked and disbelieved by the authorities in Napoleon III's France, anxious to modernise and to suppress suggestions of folk religion. But Bernadette held fast to her truth, and her shrine is today France's number one place of pilgrimage.

Other girl saints were disparaged for being "simpletons", like little St Germaine, the Swiss shepherdess, regarded as a village idiot (and afflicted with a skin disease) but subsequently venerated with powers of healing. Or St Zita, the lowly maid-of-all-work in 13th century Italy whose humble care for the poor came to inspire all.

These young girls were often ardently focused on their mission, self-sacrificing and unconcerned with worldly opinion. Greta seems very much in this tradition.

And just as young saints used to be regarded as role models of ideal conduct for youngsters, Greta surely fulfils this function for all of us today. If we aspire to save the planet, we should ask ourselves: "What would Greta do?"

Would Greta buy another plastic bottle of water and then throw it away, like the 220,000 plastic bottles which are chucked away daily in Ireland? And what would Greta think of the 200 million coffee cups dropped in the bin, every year, in Ireland?

Would Greta expect her parents to drive her to school (when she gets time to attend school), or would she walk or bike? Does Greta use a routine toothbrush, which is devilishly difficult to recycle? Or a bamboo one, as we all should. And shouldn't we make an effort to jettison toothpaste in a plastic tube? Impossible to recycle. Anyway, you can always clean your teeth with household salt.

Greta, we feel sure, washes her hair with organic soap products, not with shampoo from a plastic bottle. And by the way, teenage eco-warriors note, Greta's hair is not adorned with any extensions, highlighted streaks or other embellishments. Neither does she have waxed eyebrows or any cosmetics at all.

Greta surely disapproves of the fast-fashion garment industry, which leads to so many millions of throw-away garments annually, accounting for ten per cent of the world's carbon footprint, according to Oxfam. Greta would never wear deliberately torn jeans which use up extra energy, often produced in a Bangladesh sweatshop.

Does Greta plan to fly, any time soon, to Ibiza, the Greek islands, or the Canaries for a winter break? She does not. Greta won't fly anywhere. She takes trains and boats.

Shouldn't we emulate Greta and not fly? This may be getting awkward. Perhaps we could be like the actress Emma Thompson, or Harry and Meghan, and offset our every flight with tree-planting? For an average flight from New York to Europe, that's either 11, 13, or 213 trees (according to different measures of calculation) we'd need to plant each trip.

Then Greta doesn't do hypocrisy, like some people we could mention who take private flights galore and then lecture lesser humans on saving the planet and reducing emissions. She actually lives according to her beliefs.

Greta doesn't buy her fruit or vegetables wrapped up in Styrofoam and cling film. Greta, we feel sure, purchases her fresh fruit and vegetables, loosely, from a greengrocer.

She certainly wouldn't be buying runner beans flown in from Kenya, or potatoes imported from Cyprus, when such products could easily be grown on home soil.

Greta doesn't need to be told twice "save the planet - turn off the lights". Or to "turn down the heating", and just "put on another sweater when the nights chill". Or to use the washing machine sparingly, and at a time of low tariff - that's if she uses a washing machine at all.

We're very doubtful that Greta ever has recourse to a tumble-drier, that energy-gobbling apparatus.

And have we ever seen Greta with a smartphone? Their increasing use is said to be contributing to global warming. One report claims that between 17 and 125 megatons of emissions will have been caused by smartphones between 2010 and 2020. And only one per cent of discarded phones ever get recycled. Greta would surely advise fewer purchases of all gadgets, since she fiercely disapproves of the "fairytales" of "endless economic growth", which drives the merchandising of such gadgets.

Greta is a great young person, and we should all uphold her as an exemplar of high principles and dedicated ideals. But, just like those saints of old, emulating her practices might prove something of a challenge in our everyday lives.

@MaryKenny4