The life of the mind is a central theme in Harriet the Spy. Both Harriet and Ole Golly perceive the lack of intellectual curiosity as a grievous character flaw. The nanny deliberately points out this fact to Sport and Harriet when they visit Ole Golly’s mother in her tiny house and she points her out as “a woman who never had any interest in anyone else, nor in any book, nor in any school, nor in any way of life, but has lived her whole life in this room, eating and sleeping and waiting to die’” (18-19).

Harriet has no difficulty embracing the message that curiosity is important. The girl is driven by the need to know. She incessantly records facts about the people in her neighborhood as well as her classmates and teachers. She aspires to be a spy when she grows up because she believes that such a career is the best way to acquire more information. As she tells Ole Golly, “I will be a spy and know everything” (24). Just as Ole Golly insists that a life of the intellect matters, she also insists that observation for its own sake is futile.