Thus, when one is moved by cenain passions, the blood boils in the arteries and veins, intense heat spreads throughout the body, rising to the head, and the head becomes filled with such a large number of overly activated, too lively animal spirits whose impetuous flow obstructs the imagination from representing to itself anything other than the images and impressions that these spirits form in the brain, that is, the imagination is prevented from thinking about any objects other than those of thedominating passion.