In the words of Leonardo da Vinci:
On Metals – “There will issue from dark, gloomy caves something which will bring great sorrow, danger, and death on the whole human race; to many of those who seek it, it will after much suffering bring delight; but those who do not share in it will die in want and in distress. It will engender unending treason; it will drive unhappy men to commit more murders, thefts, and acts of oppression; it will breed suspicion among those who seek it; it will destroy the freedom of free cities; it will take the lives of many; it will sow among men much fraud, deceit, and treason.
O monstrous creature, it would be better for men if you returned to hell! On account of you great forests are robbed of their trees and countless animals are robbed of their lives.”
On Man’s cruelty – “There will be seen on the earth animals which constantly fight among themselves, inflicting great harm and frequently death on each other. Their enmity will know no bounds; their savage members will fell a great part of the trees in the vast forests of the world; and after they gorge themselves, they will continue to feed on their desire to inflict death and suffering and sorrow and fear and flight on all living creatures. Through their measureless pride they will seek to raise themselves to heaven, but the excessive weight of their members will hold them fast to the earth. Nothing will remain on the earth or under the earth and water that is not pursued, chased down, or destroyed; and it will be chased from country to country. Their bodies will be the grave and passageway of all the living bodies which they have killed.
O world, why do you not open and hurl into the deep clefts of your abysses and caverns and no longer show to heaven such cruel and heartless monsters?”
Both quotes by Leonardo da Vinci are from Codex Atlanticus, codex in the Ambrosiana Library in Milan. Published in eight folio volumes by Ulrico Hoepli, Milan for the Reale Accademia dei Lincei 1894-1904 and translated by Wade Baskins in his book, The Wisdom of Leonardo, pages 77-79.