All of us are at it, but no-one feels comfortable talking about it. As you sit there, reading this article, there is something everyone knows about you - you are conscious.
But, despite the fact that we all perceive the world in some shape or form, scientists and philosophers have been scratching their heads for centuries over what exactly this something is.
Does a kitten's playful behaviour demonstrate consciousness at work?
Looking at your computer screen, it might seem strange that something so ubiquitous as our everyday experience is considered a problem.
But examining the issue objectively, the question of what is going on in your head as you experience the screen and the life all around you has baffled so many great minds that it is known simply as "the hard problem".
Neuroscientists have yet to find anything in the brain they are happy calling consciousness, and philosophers are far from agreement over a way of talking about what happens after we wake up.
Undaunted by history, one psychologist believes he has the answer. The problem, says Nicholas Humphrey, Emeritus Professor at the London School of Economics, is that people have been looking in the wrong place.
One of the major effects of consciousness is to make us enjoy life and fear death. It encourages joie de vie, play and excitement in living in the world
"Scientists and philosophers have assumed all along that consciousness is somehow helping us think better, somehow improving our intelligence or our cognitive skills," he says.
Consciousness, he argues in his book Soul Dust, is not so much about thinking, but rather the way our brain generates for itself powerful feelings, colours, sounds and smells with you at the centre.
"Consciousness is a kind of theatre, it's an entertainment which we put on for ourselves inside our own heads," he says.
"We generate this magical mystery show in order to enchant the world and to give ourselves a sense of our own importance and place in it."
The brain, he adds, is an extraordinarily complex machine, which over thousands of years of evolution has "internalized" sensory responses to generate this "theatre" of experience.
This makes it possible for creatures to enjoy life, to find excitement in living in the world: we can see it in action in the kitten playing with a ball of string, or lambs frolicking in the fields.
Professor Humphrey believes that once scientists start to think about consciousness in the right way, they will eventually discover the processes that are going on in the brain to generate it.
Does computer simulation offer the key to understanding consciousness?
That might come as something of a surprise to computational scientists, who already believe they are able to simulate something like conscious neurons in the brain using "neural networks" in computers.
They work on computational systems which actually do the sensory "internalization" that Professor Humphrey believes is the basis of consciousness.
Neural networks on computers are able to "trap information about the world and make it useable" in the same way as our brains, says Igor Aleksander, Professor Emeritus in Neural Systems Engineering at Imperial College London.
While it is still "early days" in the development of these systems, he believes that by refining the computer models scientists will eventually gain a clear understanding of the way humans experience the world.
While the problem might be fairly new to computer scientists, it certainly isn't new to philosophers - who have long been trying to find the right way of talking about our experiences.
French philosopher Descartes also conceived of a "theatre" inside his skull
For Galen Strawson, a philosopher whose
review of Soul Dust
sparked an online dispute with the author, the important thing to remember is the difference between what consciousness does and what it is.
Computer models might help you understand what consciousness does, he says, but no-one can tell us more than we already know about what consciousness is. Even a five-year-old child knows what it is like to perceive colour or smell freshly cut grass.
Strawson doesn't argue that consciousness is not a physical process, taking place in the brain, but rather the physical process "just is" the experience we can already talk about.
The danger, he says, is that we approach the subject with our current knowledge of neuroscience and end up saying that something which is "really, really real" is actually an illusion.
"It's only when you think you know more about matter than we do know, that you think you've got a problem," he explains.
While Professor Humphrey's book is not likely to appease every philosopher in the field, nor every scientist, his theory has a more spiritual intent.
Consciousness, says Humphrey, lets us to talk about the human soul
His analysis of the evolution and purpose of consciousness focuses on the fact that it enables humans to have "magical" experiences of their own self.
"People tend to think that religions invented the soul. I think it's absolutely the other way around. We were spiritual beings before we were religious," he says.
The difficulty is that once this "illusion" is part of people's lives, it then raises a plethora of profound questions about the nature of life and death.
"Once we believe in the importance of our individual self and our individual soul, of course we can't bear the idea that it is going to be extinguished," he says.
"But we are material beings. Once the matter dies, the soul is going to die with it."