Showing profound compassion for those unable to comprehend the gem of the doctrine of three thousand realms in a single moment of life, the Buddha wrapped it within the five characters [of Myoho-renge-kyo], with which he then adorned the necks of the ignorant people of the latter age.

The Writings of Nichiren Daishonin, page 376
The Object of Devotion for Observing the Mind Established in the Fifth Five-Hundred-Year Period after the Thus Come One's Passing
Written to Toki Jonin on April 25, 1273