Sentence:  Now she could let out the three parakeets without fear they would be stepped on or that Stowey would let them out one of the doors ; she could dust the plants , then break off suddenly and pick up an old novel and read from the middle on ; improvise cha-chas on the harp ; and finally , the best part of all , simply sit at the plank table in the kitchen with a bottle of wine and the newspapers , reading the ads as well as the news , registering nothing on her <WSD>mind</WSD> but letting her soul suspend itself above all wishing and desire . 
Meaning of the word marked with <WSD> tags:  that which is responsible for one's thoughts and feelings; the seat of the faculty of reason