Zazen: The Koan Realized

As the sangha transitions into fall Ango from “koan summer,” Seido returns to zazen ,the “koan realized,” as Dogen Zenji calls it in Fukanzazengi (Universally Recommended Instructions for Zazen), recited daily in many Zen centers. Dogen says, “traps and snares can never reach it.” How is this so?