Final answer:
Freud believed that the unconscious mind and repressed traumatic memories prevent us from being the masters of our own lives.
Step-by-step explanation:
Freud believed that we are often not the masters of our own lives because of the unconscious mind and repressed traumatic memories. The unconscious mind, according to Freud, contains thoughts and feelings that we are not aware of and cannot control. Within the unconscious, repressed memories are stored, which can trigger responses and symptoms later in life. These unconscious processes and memories can affect our behavior and decision-making without our conscious awareness.