There are no absolute truths to cling to. No matter how certain of yourself you are, time brings change through experience.
As far as there being an "ultimate reality" behind appearances, even the concept of mind itself is incorrect in that it implies a reality or form beyond the nature of what is.
All form is ultimately arbitrary and can be pushed in any direction or manner we choose, provided we are aware enough to make a choice.
The source of divine inspiration is not the intellect. In fact, there is no source, but investigation brings us closer to true vision.