"I know this is going to upset people," she says, "but this is my passionate plea. We need enlightened patrons. Committees do not create good art. If you believe, as I suspect most of the Labour Party believes, that art is an optional add-on, and a committee should pick a few ethnically worthy people to invest in, then art will be dead in 100 years."
Labour voter she may be, but Professor Jardine's new study of the Medicis, Sforzas, Gonzagas and other free-spending dynasties of the 15th and 16th centuries, Wordly Goods, seems to have fired in her an almost missionary zeal for the rich as great art's only begetters.
The people who do the hard, unrecognised, graft, the people who make the paintbrushes, stitch the expensive garments, lay the stones that form architectural wonders ... what of them? They endure their poverty as an inevitable part of the creation of beauty.
"There will be artisans working for a pittance. That is the sacrifice we have to concede if somebody is to paint works like the 'Mona Lisa' that challenge society," she said.
"It's an irony that somebody like me has to say it, but that's the price you pay. I only wish you could have Utopia and create good art as well."
So forget state sponsorship, or the benefits of the lottery. The future of art lies with the individual. "In the United States they understand the importance of the entrepreneurial patron, and we need them in Britain. We do have some of them - the Sainsburys, the Saatchis - and the continuation of our civilisation lies with them."
They are words that will raise eyebrows in the common rooms of Britain's universities, whose members have long grown used to Professor Jardine's advocacy of left causes and multiculturalism. But her current espousal of the super-rich patron goes even further, those of the Renaissance being the shining examples. Thank God for them all, she says. It was the Renaissance that kindled the desire to purchase the rare and beautiful, and merchants and bankers, such as the Medicis, who used their money to ensure the creation of the finest artefacts.
"I'm talking about people who were powerful, who had status, but they had taste. OK, so some of them belonged to the gold-tap brigade too, but they were supremely cultivated. If they were not, they knew they needed advice, and now we are benefiting from their patronage."
Worldly Goods is described by its publisher as a new history of the Renaissance. Like the myriad other authors who have written about the period, Professor Jardine describes it as a time of scholarship, of the revival of classical styles, and the fashioning of a new cultural identity.
Unlike them, however, she sees the Renaissance as the first consumer boom. Its great, memorable works, she argues, came about because of acquisitiveness, bordering on avarice.
New-found wealth, often the profits of the silk and spice trades, was spent on exquisite possessions, from jewels and globes to paintings and sculpture. Even the colours chosen by Raphael, Titian and Leonardo hinted at a patron's affluence: for example, ultramarine, made by the grinding of lapis lazuli, and red pigments made of sulphur and silver were admired for their cost.
"Conspicuous consumption was a manifestation of power. It was the key way to demonstrate your prosperity, but at the same time it was a manifestation of taste," said Professor Jardine.
"Many of those who were collectors during the Renaissance were nouveau riche, but they did have a responsibility, just as the newly rich today have a responsibility to ensure that art flourishes."
The daughter of Dr Jacob Bronowski, the broadcaster best-known for his television series The Ascent of Man, Professor Jardine fears the deadening hand of government which pays only lip-service to the arts. "If you believe that art is just an add-on, then art will be dead," she said. "Art mattered to the patrons of the Renaissance. The Popes, for example, did understand that they were spending money for the future when they spent money on books. And for other patrons, like the Medicis, there was a sense of dynastic responsibility."
She is enthused by the passion she finds among them. "There was such a sense of exuberance. Nothing fogeyish about them," she insists, reserving her contempt for those whose appreciation of art is essentially backward- looking. With her architect husband, John Hare, she pays close attention to those who commission and comment upon today's monuments, even if they are cathedrals of commerce.
"Firms like Sainsbury's do their best to patronise young architects, even if it is only to build local supermarkets. Look at the difference between them and the Prince of Wales who appears to do little to justify his stance on modern architecture."
For people who visit the great collections in the National Gallery, the Uffizi in Florence, the Vatican museums and the Louvre in Paris, the Renaissance is one of the most evocative terms in the history of art. It conjures up images of Botticelli angels, Fra Angelico Virgins and a far-off era when some of the greatest artists the world hasknown were at the height of their powers. To Professor Jardine, however, this is not a long-lost golden age but a time with more similarities than differences to our own: "We are the Renaissance's direct inheritors.
"It was the moment when Europe acquired an identity, and we are still vigorously in the tradition of that Renaissance. It made and shaped the Europe in which we live."
But above all, she says, it was the rich who were responsible for the flourishing of art. "In a culture which values creativity enough, if people spend large sums at the top, then you have freedom of expression, the impact of that art trickles down."
Trickling down? That sounds more like Mr Major's vision of Britain than Mr Blair's. Professor Jardine, herself a collector-turned-commissioner of paintings, is unrepentant: "I know I'm going to get into trouble saying this, but it's what we need for art to survive. It's not that I'm saying these people are necessarily nice, but that it's the culture that's good."