George Washington followed the Greek example of retiring his horses who had served him well, allowing at least two majestic steeds that he had ridden during the war to simply graze and do whatever they wanted.
Also following the Greek example, there is no evidence that Washington treated his elderly slaves with such magnanimity. He always felt trapped by his financial plight.
Like him, we often find it easier to treat animals with more respect and kindness than we do our fellow humans. It is culturally appropriate for a mother to kill her own child, but woe to the one who harms a baby seal. Humans always require more personal effort and open us up to more personal risk.
Deep down, we know that owning a puppy is not really practice for taking on the responsibility of a human child. The dog will always wag its tail. The child may grow up to hate you. The dog will never demand too much of your soul. The child may require you to lay down your life…and then ask for more.
It was easy for Washington to grant his animals rest. Those animals would never ask for anything more. But granting his slaves rest would have been a truly revolutionary act, and once the image of God was once again recognized in those ensnared in the peculiar institution, it would have demanded so much more.