The Life of Reason by George Santayana — Read

Moral passions represent private interests.

In moral reprobation there is often a fanatical element, I mean that hatred which an animal may sometimes feel for other animals on account of their strange aspect, or because their habits put him to serious inconvenience, or because these habits, if he himself adopted them, might be vicious in him. Such aversion, however, is not a rational sentiment. No fault can be justly found with a creature merely for not resembling another, or for nourishing in a different physical or moral environment. It has been an unfortunate consequence of mythical philosophies that moral emotions have been stretched to objects with which a man has only physical relations, so that the universe has been filled with monsters more or less horrible, according as the forces they represented were more or less formidable to human life. In the same spirit, every experiment in civilisation has passed for a crime among those engaged in some other experiment. The foreigner has seemed an insidious rascal, the heretic a pestilent sinner, and any material obstacle a literal devil; while to possess some unusual passion, however innocent, has brought obloquy on every one unfortunate enough not to be constituted like the average of his neighbours.