By an ironic twist of auction fate, Monet’s sunset view came immediately after Lisière de bois, a marvelous landscape painted by Pissarro in 1878. The Pissarro fetched only £1.3 million ($2.5 million), little more than half the Monet’s price, making it one of the brilliant buys of the day. Admirably composed, it catches the essence of Impressionism in its first phase. The play of light on the green leaves done in thick, glittering touches of the brush and the contrast between the density of the foliage and the ethereal quality of the sky strewn with white clouds place the picture among the master’s greatest landscapes.

An equally desirable acquisition could be made that evening at a third of the Pissarro’s price. Bonnard was a versatile artist who cultivated multiple styles during his long career without heeding what others were doing, after the Nabi days of his youth. In 1929, looking at the sea from a balcony, of which the railing alone is seen, he painted a small masterpiece, La rade, with the sea and sky reduced to broad bands of mottled color. Were it not for a sketchy barge seen just above the railing and some hazy ships in the distance, the figural character of the seascape would hardly be recognizable.

La rade is not only admirable for its color harmony and delicately poetic mood but also holds an important place in Bonnard’s oeuvre, as is shown by the many exhibitions and art publications in which it has been featured. Yet it very nearly failed to sell. A lone bidder bought it for £433,250 ($851,770), which—excluding the 20 percent buyer’s premium—was well below the low estimate of £400,000 ($788,760).

If any doubts remained about the disconnect between artistic achievement and financial performance and the resulting haphazard price pattern that makes forecasting prices pretty hopeless, they would have been dispelled by the Sotheby’s evening session on June 25. The makeup of the sale—which included 56 works, versus the 81 at Christie’s—was different, and so was the mood of the room. Whether reassured by the considerable success of the previous day’s auction at Christie’s or stimulated by the higher average quality of the pictures in the Sotheby’s session, bidders jumped into the fray with greater alacrity.

The sales total at Sotheby’s—£102.2 million ($201.6 million)—was lower than the £144.4 million ($284 million) Christie’s achieved, but so was the failure rate: Only 5 of the 56 lots were bought in, compared with 15 out of 81 the night before. Prices frequently rose far above the estimates, evidencing the unrestrained bullishness that prevailed, and yet here, too, the link between aesthetics and financial triumph was tenuous.

The Sotheby’s experts made no secret that they had tailored the sale as closely as possible to the current taste of the buying public. To this end, they opted for Fauvism, German Expressionism, Surrealism and Picasso’s most provocative cartoon-style pictures, executed in just one day—in short, any paintings whose simplified outlines and highly contrasted colors give them instant punch. Ironically, the results, although brilliant, did not bear out the calculations behind these choices, the prices realized rarely reflecting the trends on which Sotheby’s experts had based their estimates.

True, the phenomenal success of the very first lot, a small view of the Parc de Saint-Cloud, near Paris, painted by Kandinsky in 1906, appeared to justify the experts’ selection process. Done in strong, contrasted colors and almost carved into the cardboard surface with the stump of the brush, the small panel belongs in a category of its own. It heralds the advent of Expressionism without actually belonging to it. Greater care is taken with its composition, and its color harmony is carefully balanced. At £1.2 million ($2.3 million), it fetched more than twice the ambitious high estimate.

Next came a Russian scene painted by Chagall in 1912 in a faux-naïf style. Although done in Paris, Les charpentiers, which indeed shows carpenters preparing building materials, is signed in the Cyrillic alphabet. Despite the great rarity of works from Chagall’s pre–World War I period, the picture merely matched the high estimate, bringing £690,850 ($1.4 million).