To the contemporary viewer, Paolo Veronese, 1528‑1588, is a conundrum. How can one of the greatest of all painters not be a great artist, too? The answer was inadvertently suggested by one of his most ardent admirers, Henry James: "Never did an artist take a greater delight in life, seeing it all as a kind of breezy festival," he wrote. "He was the happiest of painters and produced the happiest pictures in the world." Happiness is a trait that does not always play well now: we might prefer that Veronese displayed instead a hint of Michelangelo's terribilità, Leonardo's intellectual restlessness or Titian's all-encompassing human sympathy.  To his contemporaries, however, the pomp and celebration to be found in his pictures were not defects but his distinguishing triumphs. Giorgio Vasari, the Florence-centric painter and artist-biographer, was sufficiently impressed by Veronese's art and status to include the Venice-based painter in his second edition of The Lives of the Artists. He also attracted two near-contemporary biographers. Part of the reasoning behind the National Gallery's new exhibition of 50 of Veronese's paintings, the first ever large-scale show of his work here, is to gauge the true level of his merit and to ascertain whether he had depths to match his facility.  Veronese's early biographers were more interested in his use of colour. Even among the Venetian school, known throughout the rest of Italy for its bright hues, he stood out. As one 17th-century commentator, Marco Boschini, wrote in overwrought terms, he "has mixed gold with pearls, rubies, emeralds and sapphires of the best quality, and the purest and most perfect diamonds. And to flavour it he scattered the flowers most gentle that come from the East with all of the most beautiful things that Nature can make with its colours." Other painters had their own distinctive attributes; Veronese's was his palette.  We know frustratingly little about the man himself, but what evidence there is suggests an admirable character. He was said to be a decent man who never degraded "his position with low dealings; he always observed his promises and in every action he obtained praise". In 1566 he married the daughter of his former master and had four sons and a daughter. He was devoted to his family and gave his children a strong religious and moral framework.  Of his own morals and religion we have just one tantalising glimpse. In 1573 he was called before the Inquisition to explain why, in his huge painting Last Supper for the convent of Santi Giovanni e Paolo, he had included two German (and therefore Protestant) halberdiers, a servant with a nosebleed and a dwarf jester with a parrot. What, the inquisitors wanted to know, were these impious figures doing in such a holy scene? A transcript of the examination survives and is the only verbatim record of the artist's voice.  Veronese's defence was simple: "We painters use the same licence as poets and madmen." When asked "Did some person order you to paint Germans, buffoons, and other similar figures in this picture?", he went on to explain: "When I have some space left over in a picture, I adorn it with figures of my own invention." He then played the innocence card: "I had not thought that I was doing wrong; I had never taken so many things into consideration." Finally, he tried self-deprecation and humility: "I paint my pictures with all the considerations which are natural to my intelligence, and according as my intelligence understands them." (I am just a painter, he seemed to suggest, and not all that bright.)  Veronese's questioners accepted his explanations and ordered him to correct the injudicious figures within three months at his own expense. Veronese, however, did no such thing, he simply painted a new title on the picture: at a stroke, it changed from depicting the Last Supper to showing the Feast in the House of Levi. Not only was it no longer quite so pious a scene but, being a rich man, Levi would have the justification for surrounding himself with such a motley retinue. Veronese's sleight of hand worked, and he didn't hear from the Inquisition again. While his words at the examination can be read in two ways – he may indeed have been the innocent figure he appeared, unschooled and unworldly, or he may have been sassily playing the part – what is beyond doubt is his chutzpah.  The artist's assertion that when he saw a space he simply filled it with figures rings true. It was a characteristic Manet, for one, would hold against him: "So much useless effort, so much wasted space … Not a shadow of an emotion." But his ability to create a clear narrative within complex compositions was one of his greatest strengths. He may almost never have been a painter of the calm or the contemplative, but there is hardly an inch of lifeless canvas in all his works: dullness, in his eyes, was the ultimate crime. Whether or not he had profundity in his nature, he understood that pictorial effect relied on more than simply the expression of feeling – piety and delight were not incompatible.  Veronese was a Counter-Reformation painter, too, in that, in religious paintings, telling a legible story was paramount. His sumptuous colour, dramatic architectural settings and horizontal picture-planes have much of the theatre about them, and the links are intentional. Veronese wanted both the stage's otherworldliness and its sense of performance to inform his pictures. His banquets and visitations, presentations to the Virgin or The Family of Darius before Alexander are, above all, dramas.  The theatre also helps partly to explain his fascination with rich costumes. There exist two sheets of his drawings showing costumes worn by actors on the opening night of Palladio's new Teatro Olimpico in Vicenza in 1585. Veronese, an old friend of Palladio's and a collaborator, was drawing in the audience. His interest in clothes was also personal: his brother Antonio was an embroiderer who may have supplied him with costumes and samples to paint from, and Veronese himself, according to one biographer, was something of a dandy who "wore precious clothes and velvet shoes". He resembled those figures in his paintings described by Henry James, whose "glorious garments rustle in the air of the sea and their sun-lighted faces are the very complexion of Venice".  Cutting a dash was a deeply rooted part of Veronese's psychology. He was born in Verona to a stonecutter father and a mother descended illegitimately from the aristocracy: regaining what he felt was his family's true position was a driving force in his life. He trained informally with his father and then with two local painters, Antonio Badile and Giovanni Battista Caroto. His early independent commissions for grandees such as Cardinal Ercole Gonzaga, the son of Isabella d'Este, and the Giustiniani family may not have been the result of talent alone but came about through family connections.  Veronese is usually referred to as a Venetian painter, but in fact he didn't arrive in the serene republic until some time around 1555, by which time he was almost 30. And while he has traditionally been grouped with Titian and Tintoretto in the great triumvirate of Venetian art, they were not of the same generation: Titian was more than 30 years his senior and Tintoretto a decade. Although both men were to influence Veronese's art, he never forgot his home city – as evidenced, not least, by his choice of name (his real name was Caliari). Verona, unlike Venice, was a city full of Roman remains, and it was a familiarity with the classical past that he brought with him when he decided to try his luck "under a more favourable sky".  He arrived in Venice with a high reputation and was almost immediately offered prestigious commissions to paint the ceiling of the chamber of the Council of Ten (Venice's security executive) in the Ducal Palace and then three works for the Biblioteca Marciana – for which Titian awarded him a gold chain. Once in Venice, Veronese rarely left it again, apart from trips into the terraferma, Venice's area of influence on the mainland. When the Habsburg monarch Philip II invited Veronese to Spain after Titian's death to decorate the Escorial, the painter refused, saying he would be "sorry to leave his own nest for adventure".  The work he produced at home encompassed altarpieces and devotional works, mythologies and portraits and, above all, the feasting scenes that made him famous. The themes ranged from the Marriage Feast at Cana to the Feast in the House of Simon to the painting that interested the Inquisition. They are huge pictures, the Louvre's The Marriage Feast at Cana of 1562-3, for example, covers 66 square metres of canvas and contains more than 120 separate figures. Painted for the refectories of religious confraternities, these pictures gave the monks diversion, if not edification, at meal times. Eating, though, was the one thing they had incommon. Full of colour and incident, from musicians and children to the dogs he so loved to include in his work (Ruskin thought they were there to "give the fullest contrast to the highest tones of human thought and feeling"), the pictures offer a panoramic view, not of a world of biblical asceticism but one of Venetian high society and conspicuous consumption. The results were spectacular: Veronese, said one awestruck admirer, "is the treasurer of art and of colours. This is not painting, it is magic that casts a spell on people who see it."  The reason he could paint works on such a scale was because he planned the compositions carefully, making preparatory drawings of the figures, so that when he came to paint, as his biographer Ridolfi noted, "He never put his brush in the wrong place." This, and an efficient studio practice, allowed him to paint at speed; his pictures rarely show signs of reworking.  What the National Gallery exhibition also highlights is Veronese's variety. Alongside the big figure-filled mise-en‑scènes, he painted portraits of an unexpected sobriety. In the exceptional Portrait of a Gentleman of 1555 from the Pitti Palace, for example, he worked in monotone, reserving his bravura touches for the man's lynx-fur lined coat. His 1555-60 portrait of a lady, known as La Bella Nani, is another portrait influenced by Titian, in this case La Bella of 1536. Veronese's blonde is richly dressed in blue velvet but, as with the Titian, she is set against a black background and, rather than endowing her with his habitual happiness, he gives her a shy and anxious expression.  Titian was also the inspiration for Veronese's mythological paintings of the 1570s and 80s. The older artist's poesie – scenes of the loves of the gods taken from Ovid – inspired him to rework them in his own idiom. Venus and Adonis, Perseus and Andromeda, Mars and Venus are his own exercises in divine eroticism. Curiously, he painted at least three such subjects where the gods' amorousness is interrupted by the appearance of a startled horse or a curious dog, as if he couldn't quite take such topics seriously.  The last two decades of his life saw some diminution in quality. Demand for his works was such that he couldn't paint them all himself and he didn't keep as close an eye on his studio productions as he might have. His reputation suffered as a result. His two eldest sons and his younger brother Benedetto did much of the work and indeed, after his death, they formed a studio of their own, producing Veronese-esque works under the title Haeredes Pauli – "heirs of Paolo".  At his best, though, Veronese was an artist of extraordinary facility, one of the most inventive artists of an inventive age. His critics may sometimes dismiss him as merely an upmarket decorator, but, if they are right, his greatest commission was posthumous. Veronese died after catching a pulmonary infection during a religious procession near his country house at Sant'Angelo but, according to his biographer Ridolfi, that was simply because God had "called him to paint the blessed rooms of Heaven".
Veronese's work has long been acclaimed for its pomp and celebration – not least by Henry James. Now, the first large-scale exhibition at the National Gallery looks set to expose its drama and depth, writes Michael Prodger