Blue Notebook in dreams
A bound book of blank pages — private space reserved for your own thinking.
How blue changes the reading
Blue colour cools the symbol — calm, distance, the steady side of the spectrum. Whatever the base meaning, blue says the situation is operating at a temperature you can think in.
The base reading of Notebook
A notebook in a dream is the dream's image of a private container for thought. The notebook does not perform; it holds what you have not yet said aloud. The dream brings the notebook when there is interior material in your life that needs a place to be written down before it is acted on. An open notebook with fresh entries is the dream telling you that the practice of recording your own thinking is, currently, doing its work. A lost or filled notebook with no replacement is the dream noting that the private container you used to use is no longer available, and your thinking has been left without a home.