The most evident difference between man and animals is this: the beast, in as much as it is largely motivated by the senses and with little perception of the past or future, lives only for the present. But man, because he is endowed with reason by which he is able to perceive relationships, sees the causes of things, understands the reciprocal nature of cause and effect, makes analogies, easily surveys the whole course of his life, and makes the necessary preparations for its conduct.
"I believe that no characteristic is so distinctively human as the sense of indebtedness we feel, not necessarily for a favor received, but even for the slightest evidence of kindness; and there is nothing so boorish, savage, inhuman as to appear to be overwhelmed by a favor, let alone unworthy of it."