Tathagata and the seeker after knowledge!

Many ancient pali literature proposed the end or nirvana as 'tathagata got released'. What does it mean? Do tathagata is bound? Or Do we bound by ignorance and free with right knowledge(Samma Ditthi)? Samma Ditthi at times coincides with Thou are that, upanishadic dictiom. Five aggregates are mere empty, like mirage of real caste on matter. But, when one gives up that which is not his, he lands onto mirage. And from that mirage he see Truth or who have samma ditthi. Please any one could guide me in this regard!