Two key word objects: Intentional Inexistence, and Inner perception...
I found this book useful as an empiricist/constructivist. I had not meditated on the thought of thought as a form of perception, maybe I missed out on the concept when I read Locke and Hume a few years ago, maybe i just didn't split that hair. Either way I find that thought as a form of perception/intuition is interesting along with presentation and judgment. Also this book is important in that it is one of the early works that specifically mention intentionality as a key part of the human.He may have even been the first to formulate intentionality. This is an important work, especially if you read or want to read Edmund Husserl.