The knowledge of static electricity dates back to the earliest civilizations, but for millennia it remained merely an interesting and mystifying phenomenon, without a theory to explain its behavior, and it was often confused with magnetism. The ancients were acquainted with rather curious properties possessed by two minerals, amber (Greek : ἤλεκτρον, ēlektron) and magnetic iron ore (μαγνῆτις λίθος magnētis lithos, "the Magnesian stone, lodestone "). Amber, when rubbed, attracts lightweight objects, such as feathers; magnetic iron ore has the power of attracting iron.