The epithet “Tathagata” is an adequate expression of the relation between the universal Bodhi and particular Buddhas. Buddha’s personal life is a particular phenomenon, and the significance of his Buddhahood is lost, is a vacuity, when considered apart from the Truth he has attained and revealed to us. Yet the Truth (tatha) is a mere abstraction, a dead name, unless there appears a Tathagata in concrete human life. The true reality in the person of Buddha consists in the dignity of the Tathagata attained by a particular person, in virtue of the universal Bodhi which is the essential condition of his communion with the Buddhas of the past and of the future.
Nichiren, The Buddhist Prophet