与无意识思想相反，弗洛伊德将人类的其他思想分为两个层次:有意识和前意识。他认为意识是人类精神器官中一个微小而脆弱的部分。它是一个可以与外界联系的心理部分。在大多数情况下，意识是一种非常短暂的精神状态和暂时的现象(王，Z。， 1988，第57页)。在精神分析学中，前意识是指在某一特定时刻处于无意识状态的思想，但它们不会被压抑，可以回忆，并且能够很容易地变得有意识。因此，如Rose, J. (1986, p. 3)所说:“无意识是对一种语言的唯一防御，这种语言被冻结成纯粹的、固定的或制度化的意义，而……就其扰乱主题的能力而言，是对常识不可容忍的限度的突破。例如，弗洛伊德(1986,p. 272)用空间的表现来解释这个理论。无意识系统就像一个巨大的前厅，所有的心理冲动都聚集在这里。还有一个更小的房间，就像一个接待室。意识在这个接待室，但有一个观察者站在前厅和接待室之间。
他传输了一些脉冲信号，检查它们，然后决定这些脉冲信号可以进入接待室，也可以留在前厅。使心理冲动停留在前厅的状态称为“压抑”。弗洛伊德认为“压抑”是无意识的原型。简而言之，无意识包括人类的原始冲动和本能欲望，这些都受到文化规则和价值观的约束。意识是人在任何时候都能感觉到和体验到的思想。前意识是意识和无意识之间的一部分。前意识和意识之间没有不可逾越的界限，但意识和无意识之间的界限是不可逾越的。然而，有时候，意识和无意识之间的界限会泄露出来，而无意识“会在手势、口误(说话者没有注意到)、梦境等事情中找到间接的表达方式”(吉莉安，R。， 2001，第101页)。无论如何，正如Gillian R.(2001，第101页)所说，“根据精神分析，我们永远无法完全了解自己，因为潜意识超出了自我意识，我们有意识的自我总是有可能被无意识的游离所渗透。”
Opposite to the unconscious thought, Freud divided other human thoughts into two gradations: the conscious and the preconscious. He thought that the conscious is a tiny and feeble part in human’s psychic apparatus. It is a psychological part which can connect with the outside. In most of the time, conscious is a very short state of mind and a temporary phenomenon (Wang, Z., 1988, p. 57). And in psychoanalysis, the preconscious are the thoughts which are unconscious at some particular moment in question, but they are not repressed and are available for recall and are capable of becoming conscious easily. Therefore, like Rose, J. (1986, p. 3) said that “the unconscious is the only defense against a language frozen into pure, fixed or institutionalized meaning, and … In its capacity to unsettle the subject, is a break against the intolerable limits of common sense.” For example, Freud, S. (1986, p. 272) used the performance of the space to explain this theory. The unconscious system is just like a big antechamber, in which all the psychological impulses crowd together. And there is a smaller room which is like a reception room. The conscious is in this reception room, but there is a watcher standing between the antechamber and reception room.
He transmits some of the impulses, checks them, and decides that the impulses can go into the reception room or still stay in the antechamber. The state of making the psychological impulses stay in the antechamber is called the “repression”. Freud thought that the “repression” is the prototype of the unconscious. To be brief, the unconscious includes the original impulse and instinctive desire of human, which are disciplined by the cultural rules and values. The conscious is the thoughts which can be felt and experienced by people at any time. And the preconscious is a part between the conscious and unconscious. There is no unbridgeable boundary between the preconscious and the conscious, but the boundary between the conscious and the unconscious is insurmountable. However, sometimes, the boundary between the conscious and the unconscious leaks, and the unconscious “finds indirect expression in things like gestures, slips of the tongue (which are not noticed by the speaker), dreams, and so on” (Gillian, R., 2001, p. 101). Anyhow, like what Gillian, R. (2001, p. 101) said, “According to psychoanalysis, we can never fully know ourselves, because the unconscious remains beyond self-consciousness and our conscious selves are always likely to be infiltrated by excursions from the unconscious”.