Evaluate the arousal intensity of the following sentence, considering the mood of the author. Give a score between 0 and 1 inclusive, where 0 is the most calm and 1 is the most energetic.
Sentence: "study the brain and the self externally. Ever since the 1920s, their science has been about observation of behavior, questionnaires, recordings of electrical brain activity. But the mind can only be known by you, the person whose mind it is."