Human brains are extremely delicate and complex machines, and they do in fact have a weak spot: the same molecules that make the brain work can also be the cause of sudden personality changes, and destroy our ability to think. Human beings are always hanging in the balance, even fighting against molecules that could (literally) destroy their own mind.
To give an example of how molecules can make a difference, in the field of cancer treatment there has been a real revolution in the last twenty-five years. Researchers have succeeded in identifying the molecular causes of many types of cancer, and have been able to create molecular solutions.
It has not always been so easy to identify the key significance of molecules in human health: just think of how the discovery of DNA came about, thanks to the tireless work of Dr Friedrich Miescher, a Swiss doctor who, having almost completely lost his hearing, and realising he could no longer hear his patients, relegated himself to his laboratory to concentrate on his experiments on pus. Thus, he discovered that, in addition to the molecules that other doctors had already written about, the pus also contained materials rich in phosphorus. Nobody realised at the time that Miescher had discovered the molecule that transmitted genetic characteristics from generation to generation, and for the next eighty years DNA was basically ignored, until 1944, when Dr. Avery, a Canadian bacteriologist who was about to retire, began studying the behaviour of bacteria, and realised that it was DNA that carried genetic traits in human beings. More recent discoveries made it possible to understand how DNA mutations can actually devastate any part of the body, but nowhere is the effect more devastating than in the brain. Knowledge of genetics has now become so vast that sometimes it is possible to identify when people are going to suffer from brain diseases even before they present symptoms: we have now reached a point where we can predict the future of the human brain like never before.