Humans inhabiting the Earth have a persistent habit of thinking about themselves as of a special kind of living creatures distinguished from all the other beings by possessing something they call consciousness. There may be different views on the adequacy of this idea, from complete denial of its real grounds to the mystic adoration of consciousness as a glimpse of God. While the both extremes lead to the impossibility of scientific study, the major part of researchers prefer to be pragmatic and adopt various kinds of "technical" approach, dealing with specific models of consciousness incorporating some of its aspects related to the particular science; however, this can only be a temporary solution, and the fundamental questions concerning the nature of consciousness arise with more vigor, when development of some research technique approaches the limits of its applicability. Therefore, it would be desirable to have a sound foundation on which a unified view on consciousness could be based, providing a common frame for all the special sciences investigating the particular manifestations of consciousness, and thus avoiding much misunderstanding due to the confusion of terms and methodological incompatibility. Such a general view cannot be produced within science and with scientific methods---this is a task for a philosopher. However, philosophy of consciousness may be unfolded in different ways, some of them oriented to the methodology of science, and some others of a rather aesthetic, or ethic turn.

Scientific study of consciousness is to carefully discriminate consciousness from the rest of the world. Such an analytical attitude necessarily puts apart "consciousness" and "not consciousness", opposing them. As it always happens, oppositions like that can only be established in a limited domain, and science should never be considered as the only available way of comprehending consciousness. Thus, it is nonsense to ask science how it feels to be conscious, or how a conscious being ought to behave. These are not scientific problems, though they might also be treated analytically, resulting in a new directions of scientific research---which however deal with specifically scientific formulations answering to questions quite different from original.

Still, any study of consciousness, scientific or not, has to reflect three main aspects, which I will conventionally refer to as:

1. Ontology of consciousness: what is the place of consciousness in the hierarchy of Nature?
2. Epistemology of consciousness: is it possible for conscious beings to comprehend themselves?
3. Ethics of consciousness: what is consciousness for and why comprehend it?