Nichiren Daishonin states in “Letter to Lord Ni’ike”:
It is said that the Kankucho bird in the Snow Mountains suffers the cold at night, and cries out that it will build a nest after dawn. But when the sun rises, it is lulled to sleep in the warmth of the morning sun, and again, does not build its nest. It continues to screech uselessly throughout its whole life. The same applies to humans.