“Indeed, the line between perceiving and hallucinating is not as crisp as we like to think. In a sense, when we look at the world, we are hallucinating all the time. One could almost regard perception as the act of choosing the one hallucination that best fits the incoming data.”

“Self-awareness is a trait that not only makes us human but also paradoxically makes us want to be more than merely human. As I said in my BBC Reith Lectures, “Science tells us we are merely beasts, but we don’t feel like that. We feel like angels trapped inside the bodies of beasts, forever craving transcendence”

“One of the first things we teach medical students is to listen to the patient by taking a careful medical history. Ninety percent of the time, you can arrive at an uncannily accurate diagnosis by paying close attention, using physical examination and sophisticated lab test to confirm your hunch (and to increase the bill to the insurance company).”

“Yet as human beings we have to accept-with humility-that the question of ultimate origins will always remain with us, no matter how deeply we understand the brain and the cosmos that it creates.”

“I found myself drawn to biology, with all its frustrating yet fascinating complexities. When I was twelve, I remember reading about axolotls, which are basically a species of salamander that has evolved to remain permanently in the aquatic larval stage. They manage to keep their gills (rather than trading them in for lungs, like salamanders or frogs) by shutting down metamorphosis and becoming sexually mature in the water. I was completely flabbergasted when I read that by simply giving these creatures the “metamorphosis hormone” (thyroid extract) you could make the axolotl revert back into the extinct, land-dwelling, gill-less adult ancestor that it had evolved from. You could go back in time, resurrecting a prehistoric animal that no longer exists anywhere on Earth. I also knew that for some mysterious reason adult salamanders don’t regenerate amputated legs but the tadpoles do. My curiosity took me one step further, to the question of whether an axolotl—which is, after all, an “adult tadpole”—would retain its ability to regenerate a lost leg just as a modern frog tadpole does. And how many other axolotl-like beings exist on Earth, I wondered, that could be restored to their ancestral forms by simply giving them hormones? Could humans—who are after all apes that have evolved to retain many juvenile qualities—be made to revert to an ancestral form, perhaps something resembling Homo erectus, using the appropriate cocktail of hormones? My mind reeled out a stream of questions and speculations, and I was hooked on biology forever. I found mysteries and possibilities everywhere.”

“Even though its common knowledge these days, it never ceases to amaze me that all the richness of our mental life - all our feelings, our emotions, our thoughts, our ambitions, our love life, our religious sentiments and even what each of us regards us his own intimate private self - is simply the activity of these little specks of jelly in your head, in your brain. There is nothing else.”

“The human brain, it has been said, is the most complexly organised structure in the universe and to appreciate this you just have to look at some numbers. The brain is made up of one hundred billion nerve cells or "neurons" which is the basic structural and functional units of the nervous system. Each neuron makes something like a thousand to ten thousand contacts with other neurons and these points of contact are called synapses where exchange of information occurs. And based on this information, someone has calculated that the number of possible permutations and combinations of brain activity, in other words the numbers of brain states, exceeds the number of elementary particles in the known universe.”