Li Hongzhi writes in his Zhuan Falun,
When Sakyamuni became enlightened under a Bodhi tree, he did not reach the Tathagata level right away. He was also constantly improving himself during the forty-nine years of his Dharma teaching. Whenever he upgraded himself to a higher level, he looked back and realized that the Dharma he just taught was all wrong. When he made progress again, he discovered that the Dharma he just taught was wrong again. After he made further progress, he realized again that the Dharma he just taught was wrong. He constantly made such progress during his entire forty-nine years. Whenever he reached a higher level, he would discover that the Dharma he taught in the past was at a very low level in its understanding. He also discovered that the Dharma at each level is always the manifestation of the Dharma at that level, that there is Dharma at every level, and that none of them is the absolute truth of the universe. The Dharma at high levels is closer to the characteristic of the universe than that of lower levels. Therefore, he stated: “No Dharma is definitive.”
Ramalinga Adigal too has spoken of the various stages of spiritual experiences and its indefinite nature. I have tabulated these stages below. (Source: AN INTRODUCTION TO THE PHILOSOPHY OF RAMALINGA SWAMI by Dr C Srinivasan, published by Ilakkia Nilayam, Tiruchi, 1968)
Ramalinga Adigal transformed his body into that of Pranava Deham or the body of grace, merging with Arutperunjhoti, hence conquering death. He acknowledges that there are still higher stages that he hesitates to express.