Phillip Yancey, What's So Amazing About Grace, Zondervan, 1997, p. 83
I once shared a meal with two scientists who had just emerged from the glass-enclosed biosphere near Tucson, Arizona. Four men and four women had volunteered for the two-year isolation experiment. All were accomplished scientists, all had undergone psychological testing and preparation, and all had entered the biosphere fully briefed on the rigors they would face while sealed off from the outside world. The scientists told me that within a matter of months the eight "bionauts" had split into two groups of four, and during the final months of the experiment these two groups refused to speak to each other. Eight people lived in a bubble split in half by an invisible wall of ungrace. Frank Reed, an American citizen held hostage in Lebanon, disclosed upon his release that he had not spoken to one of is fellow hostages for several months following some minor dispute. Most of that time, the two feuding hostages had been chained together.