The basic tenet of Natural Law . . . is that we should treat others as we would like them to treat us, that we should not do to another what we would not want another to do to us. In other words, the Natural Law is simply that we should recognize in every other human being the same nature, the same needs, the same rights, the same destiny as in ourselves. The plainest summary of all the Natural Law is: to treat other men as if they were men. Not to act as if I alone were a man, and every other human were an animal or a piece of furniture.
– Thomas Merton, New Seeds of Contemplation, page 76.
This passage, which I discovered during a recent revisit to New Seeds, was the last thing I expected. Merton captures here better than I can the essence of natural law I learned first through Lincoln’s fixation on the Declaration’s equality clause.