When Words Do Not Speak: It can be difficult to open up to a complete stranger about your deepest and darkest emotions. Sometimes, we are taught to suppress our emotions and put on a blank face, even when experiencing inner turmoil. In art therapy, words are not always necessary. A mere lump of clay or a blank canvas can be far less threatening than giving voice to painful feelings, words, or images.

http://www.goodtherapy.org/blog/art-therapy-depression-expression-0619125