Astonishingly, in spite of decades of research, there is no agreed theory of cancer, no explanation for why, inside almost all healthy cells, there lurks a highly efficient cancer subroutine that can be activated by a variety of agents - radiation, chemicals, inflammation and infection.
Although the elusive 'cure' may be a distant dream, understanding the true nature of cancer will enable it to be better controlled and less menacing.
Most research into life's murky origin has been carried out by chemists. They've tried a variety of approaches in their attempts to recreate the first steps on the road to life, but little progress has been made. Perhaps that is no surprise, given life's stupendous complexity.
Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.
My feeling is that scientific method has the power to account for and interlink all phenomena in the universe, including its origin, using the laws of nature. But that still leaves the laws unexplained.
The vast majority of terrestrial species are in fact microbes, and scientists have only begun scratching the surface of the microbial realm. It is entirely possible that examples of life as we don't know it have so far been overlooked.
It is possible that a scientific discovery will be made that humans will later regret because it has awful consequences. The problem is, we probably would not know in advance and, once the discovery is made, it cannot be undiscovered.
We will never fully explain the world by appealing to something outside it that must simply be accepted on faith, be it an unexplained God or an unexplained set of mathematical laws.