“Just about every adult human being back then had a brain weighing about three kilogrammes! There was no end to the evil schemes that a thought machine that oversized couldn't imagine and execute. So I raise this question, although there is nobody around to answer it: Can it be doubted that three-kilogramme brains were once nearly fatal defects in the evolution of the human race?”

“I was taught that the human brain was the crowning glory of evolution so far, but I think it's a very poor scheme for survival. ”

“The talent for self-justification is surely the finest flower of human evolution, the greatest achievement of the human brain. When it comes to justifying actions, every human being acquires the intelligence of an Einstein, the imagination of a Shakespeare, and the subtlety of a Jesuit.”

“He always reminded us that every atom in our bodies was once part of a distant star that had exploded. He talked about how evolution moves from simplicity toward complexity, and how human intelligence is the highest known expression of evolution. I remember him telling me that a frog's brain is much more complex than a star. He saw human consciousness as the first neuron of the universe coming to life and awareness. A spark in the darkness, waiting to spread to fire.”

“There is something at the bottom of every new human thought, every thought of genius, or even every earnest thought that springs up in any brain, which can never be communicated to others, even if one were to write volumes about it and were explaining one's idea for thirty-five years; there's something left which cannot be induced to emerge from your brain, and remains with you forever; and with it you will die, without communicating to anyone perhaps the most important of your ideas.”

“A three-day-old human embryo is a collection of 150 cells called a blastocyst. There are, for the sake of comparison, more than 100,000 cells in the brain of a fly. The human embryos that are destroyed in stem-cell research do not have brains, or even neurons. Consequently, there is no reason to believe they can suffer their destruction in any way at all. It is worth remembered, in this context, that when a person's brain has died, we currently deem it acceptable to harvest his organs (provided he has donated them for this purpose) and bury him in the ground. If it is acceptable to treat a person whose brain has died as something less than a human being, it should be acceptable to treat a blastocyst as such. If you are concerned about suffering in this universe, killing a fly should present you with greater moral difficulties than killing a human blastocyst.Perhaps you think that the crucial difference between a fly and a human blastocyst is to be found in the latter's potential to become a fully developed human being. But almost every cell in your body is a potential human being, given our recent advances in genetic engineering. Every time you scratch your nose, you have committed a Holocaust of potential human beings.”