Every year I have to face a terrible moment of truth.
It happens the first morning of every summer when I'm in a warm and sunny place with friends and relatives. The drinks are flowing, the music is playing.
Everyone is happy. Except for me.
I am stretched like one of Ed Sheeran's guitar strings.
To go swimming, which I really want to do, I'll have to take off my shirt. In public.
The upper part of my body is never a beautiful sight, but at this point in summer, its faults are comically accentuated by the "tan T-shirt" that reveals the light brown ends that incongruously protrude from a pinkish-white bust.
It's an overwhelming picture that I can normally repress during the winter months, but to my horror it reappeared in an unwanted flashback on Thursday afternoon when I was at the National Gallery in London.
I was visiting the Institution of Trafalgar Square to see two parts of a panel painted by the great Renaissance master Andrea Mantegna (c. 1431-1506), which had not been exhibited together for about 500 years. United, they describe the story of Christ shortly after his crucifixion.
The lower panel is The Descent of Christ in Limbo (c 1492); the upper piece gives us the second part, The Resurrection of Christ (c 1492).
There was a lot of excitement about their reunification, which is great, but in all honesty they make a very strange couple.
The upper panel has been cleaned up a centimeter from its waist, with the central figure lying under Christ's feet and attracting all the attention in its brightly appealing orange t-shirt and socks matched to the knee.
Meanwhile, the panel below is as understated as an annual convention of teetotallers, with the faded red pigment of Christ's ample garment the most vivid element of a tonally harmonious painting. It is the stark contrast between the two that evokes the image of my humiliation for the holidays.
The fact that the upper painting was given full conservative treatment while the image below is no one's fault – they have different owners. But given the story we are facing, the two images have always been designed to be seen as one, it seems a strange decision to present them when they are in such dramatically altered states.
It makes them appear as entities separated by different artists of different times. How, in fact, they could be.
The upper panel has long been thought of as the work of a less experienced Mantegna artist.
His attribution was seriously questioned at the beginning of the twentieth century, since the curators believed that he was an apprentice in the study of Mantegna, or perhaps one of the sons of the artist, or even a copy made at a later time. That opinion changed at the beginning of this year when Giovanni Valagussa, curator of the Accademia Carrara di Bergamo, owner of The Resurrection of Christ, took the opportunity to spend some time Time in the warehouses while the gallery was being renovated.
It happened on the painting and he thought it was too good to be a minor artist.
Then he noticed the tip of a cross at the bottom of the image, which seemed to be positioned at the entrance to a tunnel or cave. This made Valagussa think. Perhaps this unloved image covered with faded paint could be part of a larger composition.
After some investigative work, the curator found the perfect correspondence: the undisputed painting of Mantegna, The Descent of Christ in Limbo, which is privately owned. He immediately identified the stick in Christ's left hand and saw that it was cut at the top. What if he put his picture over an image of The Descent, lining up the little cross at the foot of his image to the pole below?
The result was surprising.
Not only was the cross perfect, but once in place, the entire composition connected like a puzzle to create an overall design that knew that Mantegna had produced many times. Further research revealed that both images were painted using egg tempera on a poplar wood panel with aligned nail holes, suggesting that they were once held together by the same witness.
This led to the conclusion that they once were part of an altar panel in the chapel of the Ducal Palace in Mantua, in northern Italy, where Mantegna lived for 50 years, having been hired by the ruling family Gonzaga as court painter.
He was born not far away in Padua, in a modest family (his father was an illiterate carpenter), who would never have imagined that their boy would grow up to become an artist of nobility fame, living in a wonderful house himself designed .
As the artist managed to climb the ladder of life so successfully it is evident in the exhibition of the National Gallery, Mantegna & Bellini, where the two panels were reunited on Thursday.
In the first hall of the show, which shows how the two artists and brothers-in-law have striven for one another, there is a portrait of St. Mark the Evangelist (c 1448).
It is a wonderful painting, painted when Mantegna was only 17 or 18 years old and already showed an extraordinary talent for naturalism and perspective. OK, the thumb on San Marco's right hand seems to be embedded in his jaw, but other than that it's a remarkable achievement for one so young.
Mantegna may not be as famous as the big three: Leonardo, Michelangelo and Raffaele (the artists, not the Ninja Turtles), but when you see this show you wonder why it is. When he was at the top of the form, he was a pioneer and skillful as the great three of the Renaissance who arrived shortly thereafter.
If you want a masterclass in the art of foreshortening, look no further than this exhibition, where Mantegna proves she can convince in a way that Bellini, technically gifted, can not.
All of which makes the introduction of the hyper-clean The Resurrection of Christ jar a little. You can understand why the curators wanted to show their discovery, but it feels rushed.
Strangely, the paintings do not really look very beautiful together: the frames do not match, the images are too far apart and the nature of the lifting of the upper panel looks coarse compared to the aged image with grace below.
It is a three-star exhibition in a five-star show.