180) . The implication here is that the contributions of individuals within a group can reflect the entire group. For example, an orchestra is made up of musicians playing different instruments that, when played together, produce a harmonious sound. Every musician plays chords and if played out of key they can have a negative impact on the sound. The history of therapy as a science has made great strides in the application of treatment. What was once the basis of individualistic perspectives centered on one person is now the expansion of horizons, moving to a broader set of concepts that investigates the family system as a whole. ReferencesChabot, D. R. (2011). Family systems theories in psychotherapy. In J. C. Norcross, G. R. VandenBos, D. K. Freedheim (Eds.), History of psychotherapy: Continuity and change (2nd ed.) (pp. 173-202). American Psychological Association. doi:10.1037/12353-006 Gurman, A. S., & Snyder, D. K. (2011). Couples therapy. In J. C. Norcross, G. R. VandenBos, D. K. Freedheim (Eds.), History of psychotherapy: Continuity and change (2nd ed.) (pp. 485-496). American Psychological Association. doi:10.1037/12353-029Skinner, B. F. (1953). Science and human behavior. New York.