For me this is one of the most influential book for the practicing computer scientist. But really this is applicable to any field I guess. It outlines J.Weizenbaum's thoughts on the responsibility of each generation to carefully chose the set of problems they consider important enough to be tackled. Most importantly though he stresses the importance to refuse to work on problems that are unethical or morally unjustified. This resonates with me as I think that it is critically important to think and reflect the possible consequences of your own actions. Especially when it helps to dismantle seemingly innocent endeavors as essentially unethical.