This painting is a draft and sketch of Van Gogh's famous acrylic painting "The pink peach tree". He actually did a few different versions in acrylic instead of just using watercolour . We can see that he is testing out the use of complementary colours on the contrasting sky and muddy ground using the optical colour mixing technique in this painting. He also applied the skill wet on wet on the gradient sky, creating a positive white space for the clouds. We can also see the tree is drawn with delicate thin lining with a mixture of gradient blending on the background. I found this sketch inspiring because it is talented to apply multiple techniques within one sketch including art forms.