The sixth and final section of the exhibition is practically impossible to summarize, so vast is it that it occupies an entire floor of the Esedra di Levante at Villa Manin. With around sixty works, it accounts for half of the entire exhibition. In short, this extraordinary section could almost stand as an exhibition on its own. It is devoted to the combination of vast natural elements—the mountains, the sea, the sky—as the most direct expression of boundaries in the universe. Throughout our exploration of spaces, we are constantly called to seek in these elements of the universe the sense of a boundary that sometimes overwhelms us with its cosmic immensity.

The comparison between nineteenth-century American painting and European painting of the same century perhaps reaches its highest point in the section devoted to the image of the mountain. This is a primary element that characterizes the heroic dimension of the boundary sought in nature and within oneself. The figure of Caspar David Friedrich, the immense German Romantic artist, dominates the beginning, with a couple of versions of his painted mountains, one of which is shrouded in morning mist. The Romantic inspiration associated with this representation reappears very soon in American painting, already by the late 1820s with Thomas Cole, and later with painters such as Albert Bierstadt and Sanford Robinson Gifford.

But it is clearly with Cézanne and his iconic Mont Sainte-Victoire that this representation in the exhibition reaches its peak. The landscape created by the master from Aix is a true sacred place, imbued with both strength and spirit. In the Swiss Alps, it is Giovanni Segantini—also featured in the exhibition—who unites the image of the peaks with the eternal essence of nature.

Finally, the image of the sky, which represents par excellence the place of a boundary that the painter continually pushes further. It is at the beginning of the nineteenth century that it assumes an autonomous and independent form, no longer merely one of the possible settings of historical representation.

It begins with the much-remembered triad of leading Romantic painters—still Friedrich and Turner, this time joined by John Constable. Eugène Boudin, Monet’s master, drew inspiration from their works. From Boudin, displayed on a single wall, is a series of small oil studies executed on the motif of the beaches of Normandy. Following these are the domestic skies of the Impressionists, from Monet to Alfred Sisley to Camille Pissarro.

The final rooms of the exhibition are unforgettable. The transition from the nineteenth to the twentieth century is marked by skies painted by incredible artists—from Edvard Munch to Monet, from Piet Mondrian to Edward Hopper to Emil Nolde. Enchanting is the wall featuring several of Monet’s water lilies, where the Normandy sky, with its clouds, is reflected in the pond at Giverny.

Up to the transition toward the flat skies of De Staël over the Seine in Paris, culminating in the inner skies of an immense and definitive painter, Mark Rothko.