BOSTON, MA.- Imitation may be the sincerest form of flattery, but for Vincent van Gogh, it was a means of self education for the artist in the 1880s, who copied numerous works by Jean-François Millet to teach himself how to draw and paint. The visual dialogue that ensued between master and student is the focus of Visiting Masterpieces, an ongoing series at the Museum of Fine Arts, Boston (MFA), which showcases great art from museums and private collections around the world within the context of the MFAs encyclopedic collection. To inaugurate the series, the Museum welcomes van Goghs “The Sower” (1888), on loan from the Van Gogh Museum in Amsterdam, to Boston for juxtaposition with the work that inspired it, Millets The Sower (1850), one of the MFAs celebrated masterpieces. The paintings, which have never before been seen