Wikipedia
A grook ("gruk" in Danish) is a form of short aphoristic poem or rhyming aphorism, created by the Danish poet, designer, inventor and scientist Piet Hein, who wrote over 7000 of them, mostly in Danish or English. They have been published in 20 volumes. Some say that the name is short for "GRin & sUK" ("laugh & sigh" in Danish), but Piet Hein said he felt that the word had come out of thin air. The contemporary "Hunden Grog" (Grog the Dog) stories by fellow cartoonist Storm P. has, in public opinion, been regarded as an inspiration.
Piet Hein's gruks first started to appear in the daily newspaper " Politiken" shortly after the Nazi Occupation in April 1940 under the signature Kumbel Kumbell. The poems were meant as a spirit-building, yet slightly coded form of passive resistance. The grooks are multi-faceted and characterized by irony, paradox, brevity, precise use of language, rhythm and rhyme, and an often satiric nature.
THE ROAD TO WISDOM
The road to wisdom?—Well, it's plain and simple to express:
Err
and err
and err again,
but less
and less
and less.
— Piet Hein
"Taking fun as simply fun
and earnestness in earnest
Shows how thoroughly thou
none of the two discernest"
- Piet Hein
"It may be observed, in a general way,
that life would be better, distinctly
If more of the people with nothing to say
were able to say it succinctly"
- Piet Hein