En Plein Air, or plein air painting, is the act of painting outdoors. This method contrasts with studio painting or academic rules that might create a predetermined look. The theory of ' En Plein Air ' painting is credited to Pierre-Henri de Valenciennes { 1750 - 1819 } first expounded in a treatise entitled Reflections and Advice to a Student on Painting, Particularly on Landscape {1800}¹ - Wikipedia.
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