Below is an extract from the book 'A short history of nearly everything' by Bill Bryson

Welcome . And congratulations. I am delighted that you could make it. Getting here wasn't easy, I know. Infact, I suspect it was little tougher than you realize.

To begin with, for you to be here now trillions of drifting atoms had some howto assemble in intricate and curiosly obliging manner to create you. It's an arrangement so specialized and particular that it has never been tried before and will only exist this once. For the next many years (we hope) these tiny particles will uncomplainingly engage in all billions of deft , co-operative efforts necessary to keep you intact and let you experience the supremely agreeable but generally under appreciated state known as existence.

Why atoms take this trouble is a bit of a puzzle. Being you is not a gratifying experience at the atomic level. For all their devoted attention , your atoms don't actually care about you - indeed, don't even know that you are there. They don't even know that *they* are there. They are mindless particles after all and not even themselves alive. ( It is a slightly arresting notion that if you were to pick yourself apart with tweezers, one atom at a time, you would produce a mound of fine atomic dust, none of which had ever been alive but all of which had once been you.) Yet somehow for the period of your existence they will answer to a single rigid impulse: to keep you you.

The bad news is that atoms are fickle and their time of devotion is fleeting - fleeting indeed. Even a long human life adds upto only 650,000 hours. and when that modest milestone flashes into view, or at some other point thereabouts, for reasons unknown, your atoms will close you down, then silently disassemble and go off to be other things. And that's it for you.

Still you may rejoice that it happens at all. Generally speaking in the universe it doen't, so far as we can tell. Thi is decidedly odd because the atoms that so liberally and congenially flock together to form living things on Earth are exactly the same atoms that decline to do eslewhere. Whatever else it may be, at the level of chemistry life is fantastically mundane: carbon, hydrogen,oxygen,nitrogen, a little calcium, a dash of sulphur, a light dusting of other very ordinary elements- nothing you wouldn't find in any ordinary pharmacy- and that's all you need. The only thing special about the atoms that make you is that they make you. That is ofcourse the miracle of life.

Whether or not atoms make life in other corners of the universe, they make plenty else; indeed , they make every-thing else.
Without them, there would be no water or air or rocks, no stars and planets, no distant gassy clouds or swirling nebulae or any of the other things that make the universe so agreeable material . Atoms are so numerous and necessary that we easily overlook that they needn't actually exists at all.

There is no law that requires the universe to fill itself with small particles of matter or to produce light and gravity and other properties on which our existence hinges. There needn't actually be a universe at all . For a very long time ther wasn't . There were no atoms and no universe for them to float about in. There was nothing- nothing at all anywhere.

So thank goodness for the atoms. But the fact that you have atoms and that they assemble in such a willing manner is only part of what got you here. To be here now, alive in the twent-first centuary and smart enough to know it , you also had to be the beneficary of an extraordinary string of biological good fortune. Survival on Earth is surprisingly tricky business. Of the billions and billions of species of living things that have exisited since the dawn of time, most- 99.99% - are no longer around. Life on Earth is not only brief but dismayingly tenous. It is a curious feature of our existence that we come from a planet that is very good at promoting life but even better at extinguising it.

I decided that I would devote a portion of my life to reading books and journals and finding saintly , patient experts prepared to answer a lot of outstandingly dumb questions. The idea is to understand and appreciate - marvel at , enjoy even- the wonder and accomplishment of science at a lavel that is not too technical or demanding but isn't entirely superficial either.