source, primary, level

原 is composed of 厂 (cliff) and a variant of 泉 (spring). 厂 depicts a steep rock wall, while 泉 is a pictograph of water flowing out from a rock crevice. Thus, 原 conveys the idea of the source of water, but this meaning was later taken over by 源. Nowadays, 原 means origin or fundamental. Due to alluvial processes, the areas around rivers or water sources are often broad and flat land, so 原 is also used to refer to a plain or plateau.