Mercati posed the question to himself, why would anyone prefer to manufacture artefacts of stone rather than of metal, a superior material? His answer was that metallurgy was unknown at that time. He cited Biblical passages to prove that in Biblical times stone was the first material used. He also revived the 3-age system of Lucretius, which described a succession of periods based on the use of stone (and wood), bronze and iron respectively. Due to lateness of publication, Mercati's ideas were already being developed independently; however, his writing served as a further stimulus.