I am sure you are wondering what pizza has to do with mental health. It is much more than enjoying a tasty slice or two. A slice of pizza represents a part of a whole and introduces us to the concept of systems theory. The systems concept helps us process a lot of information in a more orderly way, to be able to go back and forth between the whole and its parts, understanding the interaction between the forest and its trees. We can examine the individual trees while at the same time taking in the picture of the entire forest.