We can distinguish between two kinds of mind function: awareness (the dispassionate observer) and the jumble of automatic processes (conscious, semiconscious and subconscious) that dictate our emotional states, thoughts and much of our behaviour. One of the first scientists to recognize this distinction was the great Canadian neurosurgeon Wilder Penfield. “Although the content of consciousness depends in large measure on neuronal activity, awareness itself does not,” Penfield wrote. “To me it seems more and more reasonable to suggest that the mind may be a distinct and different essence from the brain.”

Addiction is any repeated behaviour, substance-related or not, in which a person feels compelled to persist, regardless of its negative impact on his life and the lives of others. Addiction involves:

1. compulsive engagement with the behaviour, a preoccupation with it;
2. impaired control over the behaviour;
3. persistence or relapse, despite evidence of harm; and
4. dissatisfaction, irritability or intense craving when the object—be it a drug, activity or other goal—is not immediately available.