Thought is real. The content of thought is not.
So what does that mean, and what does it have to do with freedom or liberation?
Thoughts are real events which actually occur. There's no doubt that they appear, and even if the source or form can't be pinpointed, they are a phenomenon with presence. They happen, and only one at a time. There's no such thing as multitasking when it comes to thought.
Think about picking up that object in front of you while simultaneously thinking about the object itself. While a switching back and forth may happen quickly, the thoughts are never simultaneous. There's a distinct switch between the two, and EXPERIENTIALLY, there's a whole lot of difference in each of those types.
The first thought involves a mechanical action on the part of the brain and body. It's a functional thought in that it can directly lead to a "how to", to performing an immediate physical action. The second thought is a reflection or mental commentary wholly unnecessary to the action itself. It's useless except for entertainment value, and what's more, the commentary likely includes judgments as to whether you "like" the object, or "dislike" it.
How much of the process of sustaining physical life is related to commentary?
But what percentage of "your" thought fits into that second category?