By emphasizing the importance of unconscious processes as causes of mental illness (and later of most human behavior), this band of individuals set themselves apart not only from the psychologists of the time but also from the medical profession. The medical profession had been strongly influenced by the mechanisticpositivistic philosophy, according to which physical events caused all illness. For example, physicians explained abnormal behavior in terms of brain damage or biochemical imbalance. If they used the term mental illness at all, it was as a descriptive term because they believed that all illnesses have physical origins