By Sam Harris, via his blog

The universe is filled with physical phenomena that appear devoid of consciousness. From the birth of stars and planets, to the early stages of cell division in a human embryo, the structures and processes we find in Nature seem to lack an inner life. At some point in the development of certain complex organisms, however, consciousness emerges. This miracle does not depend on a change of materials—for you and I are built of the same atoms as a fern or a ham sandwich. Rather, it must be a matter of organization. Arranging atoms in a certain way appears to bring consciousness into being. And this fact is among the deepest mysteries given to us to contemplate.