I never thought pink was Vincent van Gogh's colour.
I knew his roiling yellows in light-drenched wheat fields and sunflower petals, his turbid, shape-shifting blues that transform skies and irises into oracles, his august, indomitable greens in cypresses and walls. But pastel cotton candy pink, and not on a patch of skin or floral bloom?
The shade was spilled across a cloud- veiled sky in van Gogh's Houses And Figures (1890) and it glued me to the floors of the Barnes Foundation museum in the United States earlier this year.
The medium-sized oil painting is not as widely known as other pieces in the famed Dutch artist's oeuvre, but there was no mistaking its maker; the artist's name was writ large on the canvas in his signature brushstroke, which turns static paintings into images with breath.
Against the sky with a yolky (hard- boiled) sun low on the horizon, a row of white cottages with green roofs exhale rising arabesques of smoke from rust-red chimneys. A solitary figure without discernible facial features anchors the lower right corner of the picture, a hoe resting on his right shoulder and his blue overalls interrupting the untamed grassy plain. The hue of the sky called to my mind the rhyme "Pink sky at night, sailors' delight/Pink sky in the morning, sailors' warning".
Whether the painting made in the last year of the artist's life forecasts a fine or foul day ahead, however, is immaterial; the supernatural aura of van Gogh's celestial sphere overshadows all other thoughts.
The painting was one of many that surprised me on a visit to the private museum in Philadelphia - Henri Toulouse-Lautrec's A Montrouge: Rosa La Rouge (1886-7), a portrait of a woman's erogenous spots, her ear, nose, lips, neck and wrists robbed me of two heart beats - and made me look anew at such art institutions.
Private museums are not a recent invention. Owned by an individual or organisation rather than a government body and open to public view, such museums have been around as early as the 17th century when the Ashmolean Museum opened at the University of Oxford to display artefacts and antiquities gifted by the prominent English collector Elias Ashmole.
The rise of a new class of moneyed art collectors with pockets deep enough to build temples for their art collections, though, has revived the private museum landscape and given well-established state museums a run for their money.
In recent years, private museums have sprung up around the world from the US to Australia. Among them, the Crystal Bridges Museum Of American Art in Arkansas, designed by architect Moshe Safdie to hold the collection of Wal-Mart heiress Alice Walton, the Museum of Old and New Art in Tasmania owned by professional gambler David Walsh, and the Long Museum, with two branches in Shanghai that showcase the collection of China's biggest art collectors Wang Wei and her husband Liu Yiqian.
Building a museum and keeping it open demands considerable effort and financial commitment, but for some collectors, the reward outweighs donating the works to public museums where only a small percentage of art is on display at any one time.