It is Sigmund Freud who is credited for the discovery of the unconscious and is often called the “father of psychology”. Psychiatrist and medical historian Henri Ellenberger, in Discovery of the Unconscious, describes Depth Psychology as the key to exploring the unconscious mind. Understanding what lies in the unconscious--whether repressed, forgotten, or simply never known--can help us bring meaning to our conscious lives. The unconscious makes itself known to us through symbols, that is, images that appear to us either internally or externally and suggest meaning we can relate to. If we are willing to engage with the symbols as they come to us, whether in dreams, through art, or in some other compelling way, we can learn more about ourselves and our relationship to each other and the world around us than we ever imagined.
In his book, The Symbolic Quest, Jungian analyst Edward Whitmont states, “The same images which present themselves to us as representatives of the outside world are subsequently used by the psyche to express the inner world” (p. 29). Intuiting the meaning of this object beyond what we already understand it to be is the idea of symbolic thought. Carl Jung strongly promoted living the symbolic life: taking symbolic experiences seriously and living in relationship to the unseen worlds beyond our conscious lives. Locating ourselves within a symbolic life gives us the feeling of being rooted in something bigger, of a sense of the tapestry of the world soul into which we are woven.
One portal into living the symbolic life is paying attention to our dreams. Freud wrote the groundbreaking work, Interpretation of Dreams, on the topic in 1900. Jung's work on dreams suggested dreams are the royal road to the unconscious and he promoted analysis and amplification of dreams as a way to receive the message the unconscious is attempting to deliver. Contemporary archetypal psychologist James Hillman promotes interacting with dream symbols on their own turf, dialoguing with them and allowing their autonomous energy (that of the psyche) to speak directly to us. Whichever technique you use, you are sure to learn something new about yourself and your connection to the world through them. For a great example of dream interpretation which I enjoyed, check the recent article "Whale Dreaming" by Jungian analyst Barry Williams along with Renata Ritzman in Sacred Fire magazine (Issue 11):
http://www.sacredfiremagazine.com/Subscribe/IssueGallery/IssueEleven/tabid/241/Default.aspx or check out Hillman's Dream and the Underworld.