Known as one of the most expressive artists of the 20th-century, Vincent van Gogh created numerous paintings of nature which he painted outdoor. In direct contact with his surroundings, many, if not all of his paintings are both a symbolic representation of his emotions and of the world. His painting Willows at Sunset, believed to have been done primarily as a sketch for another piece, displays the artist’s fiery nature. The violent brushstrokes and the thick application of paint suggest that the painting was done in haste as if trying to capture the descent of the burning sun who holds in this image almost an iconic importance.
(http://www.widewalls.ch/sunset-paintings/vincent-van-gogh/)