Many people are confused about just what hokku is because historically, it has differing levels with different qualities.
Hokku originated as the first verse of a kind of communal poetry game, so it is not suprising that there are many old hokku on a low quality level. There is for example, the verse of Moritake:
Rak-ka eda ni kaeru to mireba kochō kana
A fallen flower
Returning to the branch?
Looking — a butterfly!
This is just a clever twist on an old comment by the Chinese Ch’an (Zen) teacher Baoji Xiujing, that became a Japanese folk saying:
Rakka eda ni kaerazu, hakyou futatabi terasazu
The fallen blossom doesn’t return to the branch; a broken mirror will not illuminate again.
And Sōkan wrote:
Tsuki ni e wo sashitaraba yoki uchiwa kana
If to the moon
A handle were attached —
What a good fan!
Now we may think this sort of “cleverness” in hokku went out with Bashō, but that did not at all happen. In fact in the 1700s, Buson wrote this autumn verse:
Ichi gyō no kari hayama ni tsuki wo insu
One line ‘s wild-geese foothills at moon wo seal
A line of wild geese;
Above the foothills,
The moon as seal.
Ichi gyō/ichigyō（一 行）– “one line” calls to mind the vertically-written, single-line sayings — ichigyō mono –particularly Zen sayings — that were often painted on wall scrolls.
Though superior as poetry, Buson’s “line of wild geese” verse is very much like Sōkan’s verse. Where Sōkan added a handle to the moon and made an uchiwa (a kind of roundish fan), Buson has turned a line of wild geese flying in the sky into a line of calligraphy, and has turned the moon above the foothills into a painter’s round signature seal to complete the scroll. Both have used “cleverness” of imagination to make something in Nature into something made by humans.
Now one may find such verses interesting as a form of poetry because of their “cleverness,” but cleverness is not really a part of the best hokku. In good hokku, geese are geese, not a line of calligraphy; the moon is the moon, not a fan or a seal on a painting. In good hokku Nature is allowed to be what it is, undistorted by the cleverness of the writer.
Gakoku wrote (my loose translation) this spring verse:
Kasumi yori tokidoki amaru hokake-bune
Out of the mist
From time to time —
A sail appears.
In that, the mist is mist, the boat sail that appears now and then above the mist is a sail. Each is what it is, nothing is made into or imagined to be or symbolizes something else. Hokku at its best should not exhibit human cleverness, but rather should be a clear mirror reflecting Nature and humans as a part of Nature.