In this novel, Bradbury is concerned that technology has come to control people rather than people controlling technology. Technology is supposed to serve people, but in the world he envisions, it damages and dehumanizes humans. Bradbury is fearful of technology and its allure.
Bradbury illustrates this in several ways. First, Clarisse represents old-fashioned human life, before technology came to dominate people. She still likes to walk around in the natural world and enjoys experiencing nature, from the night sky to buttercups. She prefers walking to zooming past her environment in a car. She and her family prefer talking to each other to watching televised view screens. Clarisse, though she does not survive long in Bradbury's dystopia, represents vital, healthy life and stirs up Montag's dissatisfaction with his existence.
In an opposite way, Mildred represents the dangers of immersion in technology. Her life of television-watching has become so empty that she attempts suicide. Yet when she survives her suicide attempt, the allure of the view screens remains too strong, and she is quickly readdicted.
Bradbury cautions us not to let our technology get out of control, but rather to stay in touch with our humanity through real human relationships and through exploring the ideas that are learned through books.