Exchange implies equality. - David Graeber

No anarchist claims to have a perfect blueprint. The last thing we want is to impose prefab models on society anyway. The truth is we probably can’t even imagine half the problems that will come up when we try to create a democratic society; still, we’re confident that, human ingenuity being what it is, such problems can always be solved, so long as it is in the spirit of our basic principles — which are, in the final analysis, simply the principles of fundamental human decency.

"Communist society"; in the sense of a society organized exclusively on that single principle—could never exist. But all social systems, even economic systems like capitalism, have always been built on top of a bedrock of actually-existing communism.

One could well argue that if there is any human essence, it is precisely our capacity to imagine that we have one.