Pierre-Henri de Valenciennes was a French painter who lived from 1750 to 1819 (www.en.wikipedia.org/wiki/Pierre-Henri_de_Valenciennes). He was an early advocate of painting directly from nature in order to produce landscapes. While in Rome from 1778 to 1782, he used to make landscape studies at different times of the day to catch the changes in light. As a result of this practice, one of the pieces of advice he developed for fellow painters was, "Work in haste, so as to seize nature as she is".
I remembered this piece of advice with wry amusement as I sat painting in a beautiful Spanish garden, these past weeks, and struggled to keep pace with the changing light and the periodicity of flowers as they opened and closed at different times of the day. Working in the brilliant Mediterranean light of early summer is a delight, but humbling in that every hour makes a huge difference in the appearance of subject matter. Shadows on white walls that are entrancing at nine in the morning are long gone at ten o'clock. Fragrant, subtly-coloured nicotiana flowers (tobacco flowers) that are wide open at seven a.m. shut firmly a couple of hours later and do not open again until early evening... Their timing is closely linked to their attraction to moths who pollinate them enthusiastically in the nighttime hours. But painting under those conditions is another matter!
No wonder Pierre-Henri de Valenciennes was advocating speed and catching the most distinctive traits of that particular landscape when he was painting plein air in the Rome area. He, and every plein air artist since then has learned that nature is a severe task mistress when it come to painting outdoors.