What are the motifs in Wind, Sand and Stars by Antoine de Saint-Exupery?

The value of human life is a recurring idea in the story. Antoine's time spent in Spain during its civil war presents him with the startling revelation of the ease and indiscriminate generality with which lives are ended. As he watches Madrid's bombing, he considers the likelihood that the innocents being killed in that ethereal white city are children, women, and lovers—all of them minds that will now never benefit the collective human race. He imagines that lovers holding hands would be separated by bombs that would take one, leaving the other bewildered at the suddenness of her absence.