The ancient Greek philosopher Aristotle was a big fan of friendship. “Without friends no one would choose to live,” he wrote, “though he had all other goods.” The great thinker believed that our closest friends serve as a source of guidance and inspiration, to help us become the best versions of ourselves. A true friend, as he saw it, is someone who shares the same fundamental values, attitudes, and outlook on life — a kindred spirit. The quote above has also been translated as “a single soul dwelling in two bodies,” a striking description of the kind of bond two people can share. It's remarkable that some 2,000 years after Aristotle lived, his observation is still keenly felt when we find that rare and deep connection with another person.