Letters 94.58

Do you wish to know how false is the gleam that has deceived your eyes? There is really nothing fouler or more involved in darkness than these things of earth, sunk and covered for so long a time in the mud where they belong. Of course they are foul; they have been hauled out through a long and murky mine-shaft. There is nothing uglier than these metals during the process of refinement and separation from the ore. Furthermore, watch the very workmen who must handle and sift the barren grade of dirt, the sort which comes from the bottom; see how soot-besmeared they are!

Seneca, Letters to Lucilius 94.58, translated by Richard Mott Gummere