Freud

At the end of the 19th century, through listening to his patients, Freud discovered something that he named the unconscious, thus creating psychoanalysis. An unknown realm of our psyche, the unconscious rules our life in spite of us. In other words, the unconscious has a way of its own, without us being aware of it. This force that directs our life is the origin of our suffering.
Freud has found the manifestations of the unconscious in symptoms, in dreams (dreams are the royal road to the unconscious), in slips of the tongue and in faulty, “bungled” actions – when they happen, all of these phenomena seem strange and somehow very far from ourselves, from what we wanted to say or do.

Lacan

In the 1950s, Lacan launched a return to Freud; he never ceased to teach and discuss his theories. He emphasizes the link between the unconscious and language : The unconscious is structured like a language. The laws ruling the unconscious are the laws of the linguistic chain, in other words the very unique ways in which each of us expresses him or herself.
The psychoanalyst is therefore a linguist who deciphers what these words really stand for.

The work of the analysand

In order to gain access to the unconscious and modify what is wrong, psychoanalysis offers no “quick-fix” or “miracle solution,” but only “work” to be done by the analysand: to speak his or her intimate truth, following the only rule Freud set for his patients: Say everything that comes to your mind.
Talking without self-censorship means putting one’s being into play while speaking to a psychoanalyst who hears and notices things beyond what we think we are saying.
With speech as our only means, the unconscious can unfold before us and let us decipher the symptom. Only through speaking can we discover this other, unknown part of ourselves.
For Lacan, the psychoanalytical setting allows us to let the truth speak..

We are humans, and we have relations with one another only by speech
Montaigne (Essays 1, 9)