All we will ever know, that's right. Even if we had reached the highest state of awareness, we see that's the truth because it is something we have not experienced earlier, something advanced. If a cell in our body somehow finds out that it's a part of a much bigger system called human body, it is enlightened. Similarly if we find out that we are entirely something different, we are enlightened, we experience it and that becomes the truth. But truth itself is infinite. One day in the future, our mind will evolve and we might have the capability to see things much clearer. Then that experience becomes the truth. This might go on till infinity until...? Until maybe the experiment is over