A major theme of the novel is whether doing what is necessary to meet a long-term goal is more important than an individual's life. Rivière wants to show that airmail is more efficient than other means of transport. “It is a matter of life and death for us; for the lead we gain by day on ships and railways is lost at night.” He therefore puts his pilots at risk to establish its commercial viability, but it is a sacrifice that they too readily accept. Drawing on his own experience and that of his fellow-pilots, Saint-Exupéry portrays them as renouncing everything in a cause in which they believe. The relationship between themselves and their employers is not that of slave and master but of man to man: a liberty with as single constraint their submission to duty. In submitting oneself to that absolute, to which all other personal considerations are consciously subordinated, greatness is achieved in one's own eyes and in those of others.