"Singleness of purpose" nghĩa là gì?

Concentration camps (trại tập trung) were not only mills of death (cối xay thịt). They were also testing grounds (bãi thử nghiệm/thí nghiệm). Here men persisted, and in a sense fought  for survival,  with the stake always nothing  less than one's  life, with the  slightest slip a fatal error. Such  was the filth (bẩn thỉu dơ dáy), the compulsion (cưỡng bức),  the debasement (mất phẩm giá), that a person had to be  possessed  of extraordinary   powers, both  psychic and  of will, to even want to survive. The  intellectuals,  the idealists, the  men  of high  morals  had  no  chance.... Having  once made  up one's  mind  to survive, it was a necessity to follow through with a singleness  of purpose,  inconceivable  to you sheltered  people  in the  States. Such  singleness  of purpose broached  no stopping  in front  of accepted  sets of values, it had  to disregard  ordinary  standards  of morality. One  could only survive through  lies, tricks and  by somehow acquiring food to fill one's belly. The weak, the old had no chance. And so liberation  came.