It is Christmas Eve. A woman takes a tumble through a clothes rack and enters her own private NarniaThe imaginary land of magic people and animals invented by author CS Lewis.. 

She skips back and forth through time, seeing the highs and lows of her life with her sister. When she returns to the shop, she is able to buy the perfect present. 

This is the plot of The Gifting Hour, John Lewis's Christmas shopping advert.

For almost two decades, the department store's Christmas adverts have been the subject of a national conversation. 

The commercialisation of Christmas is controversial. Every year, commentators bemoan that a once-religious festival has instead become focused on buying gluttonous heaps of food and expensive presents.

Yet others note that the Christmas we celebrate now has evolved hand in hand with consumerismSociety's obsession with acquiring consumer goods.. Historian Ruth McClelland-Nugent says: "The popularisation of Christmas in the United States begins with advertising."

It is a difficult time for shops though. John Lewis has lost money three years in a row. A bumper year of Christmas shopping could save the high street - and stop town centres becoming empty wastelands.

Is Christmas shopping a virtue?

Yes! Most people like giving and receiving gifts and all acts of giving stem from buying and selling. We should stop pretending otherwise.

No! A virtuous act is one we choose to do. But society has forced us to shop at Christmas.