I was reading through a book called "Arahattamagga" or "The Path to Arahantship" composed from the experience of Luangta Maha Boowa, on how he attained the Supreme enlightenment of Arahantship.
It was so interesting and it strike me hard that we are so fortunate to still have these living Arahants that are reachable to us. The 2nd simile was, When Luangta Maha Boowa spoke of his (non duality) mental state, in which he was "neither courage or fear" and "neither harm or harmless" which is exactly what was meant in the Prajna Paramita (Mahayana Heart Sutra).
In the Heart Sutra, it was mentioned :
"Sariputra, the Characteristics of the voidness of All Dharmas
Are Non-Arising, Non-Ceasing, Non-Defiled,
Non-Pure, Non-Increasing, Non-Decreasing."
So, it seems like what Luangta Maha Boowa speak has the same gist of what was in the Prajna Paramita (Heart Sutra). And this mean, the concept of Enlightenment is the same for both Theravada and Mahayana.
Luangta Maha Boowa also mentioned that, the Buddha Dharma was so true that one needs only excerts the efforts to achieve it. Being in his positon now, he truly appreciate the Buddha's compassionate virtue to teach and guide us through the Dharma. He said the existence of Karma, rebirth, hell, heaven and all that was told by Buddha was real, as he has now had perceived them all.
May we all too, can all strive to attain Arahantship (or any other of the 3 saint hood) =P