"Buddha" or "Buddha-nature"?

"The Nirvana Sutra says: “Rely on the Law and not upon persons. . . . Rely on wisdom and not on discriminative thinking.”

To rely on the Law means to rely on the constantly abiding Law of the Lotus and Nirvana sutras. Not relying on persons means not relying on persons who do not themselves rely on the Lotus and Nirvana sutras. Even though they may be Buddhas or bodhisattvas, if they are Buddhas and bodhisattvas who do not rely on the Lotus and Nirvana sutras, they cannot serve as good friends. And how much more is this so if they are merely scholars, translators of the sacred texts, or ordinary teachers!

To rely on wisdom means to rely on the Buddha*. Not relying on discriminative thinking means that one does not rely on those who are on the level of near-perfect enlightenment or below." -- Nichiren [From How Those Initially Aspiring to the Way Can Attain Buddhahood through the Lotus Sutra]

*please note, "Buddha" not Buddha nature.