Just as using an improper tool in machinery can be devastating, choosing the wrong "jōseki" can easily be worse than improvising one's own moves. In his book "A Way of Play for the 21st Century", Go Seigen compared choosing the proper "jōseki" to choosing the proper medicine: "Pick the right one, and you feel better. Pick the wrong one, and you die." Rui Naiwei similarly remarked that "playing "josekis" is easy choosing the right one [in a game is hard." [par.]