Consciousness is a phenomenon that has fascinated thinkers and scientists throughout history. The last few decades, however, there has been an increasing academic interest in the subject. The main concern of this paper is whether all aspects of consciousness are accessible to scientific investigation. It is based on the study of relevant literature from books and scientific journals. I have considered the historical and philosophical perspectives, and, lastly, presented the problem from the point-of-view of cognitive neuroscience. One can approach consciousness from a first-person or a third-person perspective. The so-called hard problem of consciousness is explaining how neural structures and processes give rise to subjective, qualitative experience, often called qualia, thus bridging the gap between these two perspectives. Philosophical opinions on the problem of consciousness may be grouped roughly under the headings of dualistic interactionism, eliminative materialism and naturalism. Empirical approaches to consciousness are explored within cognitive neuroscience, a field that integrates methods from neural science, cognitive psychology, computer science and other traditions. Considerable effort is being put into finding the neural correlate of consciousness. Correlations between subjective awareness and neuronal activity are studied in animals and humans using a variety of techniques. Although this research shows promising progress, it remains to be seen whether scientists may ultimately conquer the hard problem of qualia. While many neuroscientists seem moderately optimistic, some philosophers are far from convinced. This reflects a difference in the way of thinking, which I suggest may be due to diverging concepts of what would be accepted as a satisfactory future explanation.