[I]f we are to believe in the Buddha’s will, we must comprehend the teachings of all the other sūtras as reflected upon the clear mirror of the Lotus Sūtra. Now, it is stated in the Lotus Sūtra: “The Lotus Sūtra is above all the other sūtras.” This means that just as Indra resides on the top of Mt. Sumeru, or a wish-fulfilling gem exists on the head of the Wheel-turning Noble King, or the moon shines over various trees, or a protuberance is seen on the head of Buddhas, the Lotus Sūtra is a wish-fulfilling gem placed above all the Buddhist sūtras.

Hōon-jō, Essay on Gratitude, Writings of Nichiren Shōnin, Doctrine 3, Pages 4.