As a genre, haiku is associated with instantly readable images that seem to connect the reader with an order beyond the human imagination. There’s a certain impersonality in haiku. The Japanese tradition of linking the image to a season, a part of the calendar year, is an economical way to that end. The seasons just happen. Pure contingency. The details of our imaginative life follow suit.
And yet in the making of a haiku there is a demand made on the poet’s self for a sense of depth of feeling. Human feelings, in their ebb and flow, have their own seasons. The depths are rarely transparent. What “triggers” emotion would be hidden if it weren’t for the image:
it’s such a relief
to see the cat on the lawn