This is the effect you see on people or yourself when you just read a book and you are so familiar with its contents. You are so excited to share what you read and do so very articulately. But this glow is short-lived. After a few days or weeks, it subsides and you forget what you read completely. Reading without note-taking is only beneficial in the short-term.
Connect this with the Baader-Meinhof Phenomenon.