Job 28:4

The flood, the place of cutting through, breaketh out from the inhabitant, that is, man opens or cuts through a shaft, away from those sojourning above, straight down into the earth; even the waters forgotten of the foot; they are dried up, they are gone away from men, literally, "where forgotten by every one's foot they dangle, far from mortals, they swing," that is, men dig their shafts down so deeply that they are entirely out of sight and ken of men walking above; they are suspended by ropes far from the surface where other men are living and going about their business. All this is done in order to bring metals up to the surface. But true wisdom cannot be so acquired.