English has several idiums that no longer make sense in today's context but still have the old meaning.
Some idioms made no sense originally and are still used today, such as "the alarm went off," when actually it sounded (went on).
Other idioms that are technically incorrect include "see the light" and dietary programs being referred to as "weight loss" rather than "mass loss" or even "waist management."
(I suppose "see the light" might be debated; we don't actually see objects. We see by the light they reflect or emit, but do we really see light? A high school physics teacher's favorite peeve was "seeing steam.")