良心
りょうしん · ryoushin · JLPT N1 · noun
conscience
良 — pictograph of a covered grain hopper
良 originated as a pictograph of a funnel-shaped device used to clean or sift grain, with a top opening, central body, and bottom outlet. From this image of selecting good grain, the meaning extended to 'fine,' 'good,' or 'excellent.' The modern shape obscures the original object.
心 — pictograph of a heart with chambers and aorta
心 is a pictograph showing a stylized heart, with strokes representing the organ's chambers and the aorta at the top. Originally meaning the physical heart, it broadened to cover mind, feelings, and intentions, since ancient Chinese thought located thinking and emotion in the heart.