The repertoire of experiences that a single brain can achieve is amazingly big. However, our brains are relatively similar in size, components and biochemistry. We have the same type of neurons and neurochemicals that a rat has. What differentiates us from animals and what explains the difference in behavior and personality among people are the connections in our brain.What is different between me and you is the type of connections that you and I have, how neurons interact with each other, how they organize and get structured. In a way, we are different but in a more important way we are very similar. The human experience is differentiated more in subtle nuisances than in fundamental, deeply alien ways. This why so many people like Coca Cola, and some Pepsi. Two choices really, and at that the same time very similar. As different humans are, I'm always amazed on how similar our thoughts, fears, desires are, even across cultures, time, sex, age. But again one can explain both how similar and how different we are in the context of modern neuroscience. The picture is not complete, not perfect but we are coming closer and closer. Few days ago, I went to a lecture, here at the Department of Psychiatry, at UW, Madison where I work. The lecturer was showing how the injection of this particular neurotransmitter was increasing the voluntary feeding amount of a rat. And then how this other was decreasing it. He plotted a graph of the amount of the chemical substance injected in very specific part of the brain versus the amount of feeding: he obtained a perfect straight line, indicating a perfect correlation between these parameters. Then another region was inhibited and the opposite effect was obtained. It is just amazing, a complex behavior modulated by a simple substance. And that is not just true for rats but the same would happen in humans under the same conditions. In fact, the scientist explained that he would like to explore the application of this finding to help people with addictions. Maybe we are a little more complex than a rat but we respond to the same chemicals, to the same stimuli. To some, it is scary that we are these physical connections between neurons, these electrical currents, these molecules but what is scary about this? These neurons, electrical forces, molecules are fascinating, beautiful in how they work and behave, and part of the miracle of existence. On the contrary, I find that invoking spirits and elves and strange superstitions as the "soul" to explain what we are, when so much beautiful real knowledge about the nature of our beings is unfolding in front of our eyes (every day brings new and fascinating discoveries in neuroscience) is a shame. And if part of what discovered is that yes, us being our physical brain then love is a chemical, our thoughts are electrical impulses, that our personality and memories are connections among neurons, and when the brain dies we also die with it, then is not just true but alright. But that is not reason for despair but it is good news and cause for action. In fact, we can do something even about the problem of death. Science can find a way to extend life. What religion promised, eternal life (a natural and just longing by an aware mind) science can actually achieve. Maybe not today, maybe not in 100 years, but one day it can and will happen. Believing in after life when it is not true, it is like believing in Santa Claus simply because it would be nice if he did exist. I agree it would be nice if Santa existed. But it doesn't so you grow up and believe in people instead. They are real and sometime they bring you gifts if you are nice to them.