"Consciousness" (French: conscience) is also defined in the 1753 volume of Diderot and dAlemberts Encyclopédie, as "the opinion or internal feeling that we ourselves have from what we do".The earliest English language uses of "conscious" and "consciousness" date back, however, to the 1500s. The English word "conscious" originally derived from the Latin conscius (con- "together" and scio "to know"), but the Latin word did not have the same meaning as the English word—it meant "knowing with", in other words, "having joint or common knowledge with another". There were, however, many occurrences in Latin writings of the phrase conscius sibi, which translates literally as "knowing with oneself", or in other words "sharing knowledge with oneself about something". This phrase had the figurative meaning of "knowing that one knows", as the modern English word "conscious" does. In its earliest uses in the 1500s, the English word "conscious" retained the meaning of the Latin conscius. For example, Thomas Hobbes in Leviathan wrote: "Where two, or more men, know of one and the same fact, they are said to be Conscious of it one to another." The Latin phrase conscius sibi, whose meaning was more closely related to the current concept of consciousness, was rendered in English as "conscious to oneself" or "conscious unto oneself". For example, Archbishop Ussher wrote in 1613 of "being so conscious unto myself of my great weakness". Lockes definition from 1690 illustrates that a gradual shift in meaning had taken place. A related word was conscientia, which primarily means moral conscience.
Research in this area has not yet reached firm conclusions, but a recent questionnaire-based study identified eleven significant factors contributing to drug-induced states of consciousness: experience of unity; spiritual experience; blissful state; insightfulness; disembodiment; impaired control and cognition; anxiety; complex imagery; elementary imagery; audio-visual synesthesia; and changed meaning of percepts. Entropic brain
The entropic brain is a theory of conscious states informed by neuroimaging research with psychedelic drugs. The theory suggests that the brain in primary states such as rapid eye movement (REM) sleep, early psychosis and under the influence of psychedelic drugs, is in a disordered state; normal waking consciousness constrains some of this freedom and makes possible metacognitive functions such as internal self-administered reality testing and self-awareness. Criticism has included questioning whether the theory has been adequately tested. Theories of origin
The origin and mechanism of subjective experience within the brain remains unknown, although several scientific theories have been proposed. Roger Penrose has said that there are four such current theories.Integrated information theory (IIT) postulates that consciousness resides in the information being processed and arises once the information reaches a certain level of complexity. Orchestrated objective reduction (Orch OR) postulates that consciousness originates at the quantum level inside neurons. The mechanism is held to be a quantum process called objective reduction that is orchestrated by cellular structures called microtubules. However the details of the mechanism would go beyond current quantum theory. Medical aspects
The medical approach to consciousness is scientifically oriented.