Over the holiday I’ve been reading the 50th anniversary edition of New Scientist (dated 18/11/2006). Amongst the articles on “The Big Questions” there are a number of thought provoking and/or revealing quotes, including the following:

One of the great outstanding scientific mysteries is the origin of life. How did it happen? When I was a student, most scientists thought that life began with a stupendous chemical fluke, unique in the observable universe. Today it is fashionable to say that life is written into the laws of nature – easy to get started and therefore likely to be widespread in the universe. The truth is, nobody has a clue.
[Paul Davies, Arizona State University]

Nothing truly revolutionary is ever predicted because that is what makes it revolutionary.
[John D Barrow, Professor of Mathematical Sciences, University of Cambridge]

[Life is] any population of entities which has the properties of multiplication, heredity and variation.
[John Maynard Smith, Evolutionary Biologist ]

Life is a self-sustained chemical system capable of undergoing Darwinian evolution.
[Noam Lahav, Hebrew University of Jerusalem]

Science is a differential equation. Religion is a boundary condition.
[Alan Turing]