It is extraordinary how very little there is in the recorded words of Christ that ties him at all to his own time. I do not mean the details of a period, which even a man of the period knows to be passing. I mean the fundamentals which even the wisest man often vaguely assumes to be eternal. For instance, Aristotle was perhaps the wisest and most wide-minded man who ever lived. He founded himself entirely upon fundamentals, which have been generally found to remain rational and solid through all social and historical changes. Still, he lived in a world in which it was thought as natural to have slaves as to have children. And therefore he did permit himself a serious recognition of a difference between slaves and free men. Christ as much as Aristotle lived in a world that took slavery for granted. He did not particularly denounce slavery. He started a movement that could exist in a world with slavery. But he started a movement that could exist in a world without slavery. He never used a phrase that made his philosophy depend even upon the very existence of the social order in which he lived. He spoke as one conscious that everything was ephemeral, including the things that Aristotle thought eternal. By that time the Roman Empire had come to be merely the orbis terrarum, another name for the world. But he never made his morality dependent on the existence of the Roman Empire or even on the existence of the world. ‘Heaven and earth shall pass away, but my words shall not pass away.’
— The Everlasting Man (1925).