In the prisoner's dilemma , a repeated series of encounters in which two unlike players, well suited to be enemies, cooperate with and become used to one another, illustrates quite well what St. Exupery intended. The essential is invisible to the eye. I believe this simple statement to be true. Logic without heart leads to death. Auschwitz was quite a logical place, organized for maximum efficiency.
Murder is very frequently a logical goal.
Our reason, if not rooted in the heart, must lead us astray. As I have said before, all problems are best solved upstream, and the river begins in the human heart. I would rather commit any error brought on by excessive compassion, if such a thing is possible, than a single error of cruelty. Whether biological in origin or given by God, compassion is a gift. It is the bonds we form to one another, and especially to our honorable enemies, that allow us to transcend our former condition.