Nichiren on why Shakyamuni is the Eternal True Original Buddha and no one else

"In the third place, Sakyamuni Buddha is the supreme leader and excellent eyes for all people. He is the bridge that enables them to cross the river of evil passions; He is the skipper who guides them over the sea of life and death; and He is the fertile field in which they plant the seed of merits..." (Kaimoku Sho, Noppa Translation)."