Moon moves down the sky
westward as tree-shadows flow
eastward and vanish.
Buson - Translated by Harry Behn, More Cricket Songs, 1971
Harry Behn (1898 - 1973) was a translator of haiku in the 60's and early 70's. Behn was a poet, children's books author, and Hollywood screenwriter, as well as a translator. His haiku translations were published by Harcourt Brace and widely read. A lot of people learned about Japanese haiku from Behn's translations.
Buson (1716 to 1784) was a haiku poet and painter. During his lifetime he was known more for his painting than as a poet. In fact, he had faded into obscurity as a haiku poet soon after his death. It was Masaoka Shiki (1867 - 1902) who rediscovered Buson and praised Buson's skill as a haiku poet in his weekly newspaper column. Since then Buson is recognized for his skill, in particular his strongly visual presentations within the haiku form.
This haiku is an example of what I call an 'extended moment' haiku. Buson is depicting a process that takes place during an entire evening; if Buson is referring to a full moon the process of the interaction between moonlight and shadows on the earth takes the entire night. In contemporary English Language Haiku discourse the idea is often put forward of the 'haiku moment', but which is meant the 'haiku instant'. I think of this approach as turning a haiku into a snapshot. But some haiku are what I think of as videos rather than photographs of a moment; these 'video' haiku encompass a process; in fact the process is primary in this type of haiku. Both Buson and Basho wrote haiku of this extended moment type and I think we should be open to that approach in the anglosphere as well.