The walls of the blood vessels of the brain are made of tightly packed cells and are nearly impermeable, forming the famous blood-brain barrier. This way, toxins in the blood cannot pass into the brain. At the same time, though, the bloodbrain barrier also prevents some helpful medications from reaching the brain.

To get around this problem, researchers at Harvard University tried a novel approach. There are certain viruses, including the rabies virus, that are able to cross the blood-brain barrier. The researchers isolated from the rabies virus a protein that seems to be responsible for "breaking through" the barrier. They separated it from the virus and combined it instead with the medication, and injected it into the blood. Not long after, the medication could be detected in the nervous tissue.

Just as the physical brain is impermeable to certain compounds, so does the mind also put up a barrier against certain thought or ideas that seem threatening to it. This type of brain barrier may be adaptive, to keep us from contending with disturbing or distracting thoughts. However, sometimes putting up mental barriers can be harmful and not allow us to move forward in life or consider new ideas.

One example of a maladaptive fixation is pessimism. The pessimist takes the worst-case view of every scenario and looks forward fearfully rather than in joyous anticipation. Pessimists are afraid of disappointment, so they prefer to expect the worst and be pleasantly surprised rather than expect the best and be disappointed. They literally block all pleasant possibilities from entering their minds.

We find such pessimism particularly regarding the prophecies of redemption. We have been in exile so long that it seems the proclamations of an imminent redemption are misguided, even silly. How can we possibly expect that the world will be transformed, that evil will be eradicated forever and people will follow only their highest instincts?

The solution, as the Harvard scientists discovered, is to use a virus as a tool. While the virus itself is exceedingly harmful, we can extract something positive from it. So, too, a pessimist can use those very same thought processes to realize how close we are to redemption. The world is a miserable place where crime is rampant? That is a sign that we have gone so low, we can only go up. We have been in exile for thousands of years? Only more proof that the exile must soon be coming to an end.

We must break through the mental barriers that prevent us from sensing that we are standing in a unique time. We are very close to our goal; we only need to let it enter our minds so we can experience redemption to its fullest.

Prof. Yirmiyahu Branover is chairman of the Center of Magnetohydrodynamic Studies and Training at Ben-Gurion University.