Traditional metal working in Mexico more. Important metal working centers include Taxco for silver, Santa Clara del Cobre for copper, Celaya for tin and Zacatecas for wrought iron. Metal working in Mesoamerica, especially of silver, gold and copper was advanced by the time the Spanish arrived, mostly concentrated in the modern states of Michoacán, Oaxaca and Guerrero. The mining and working of metals probably came to Mesoamerican cultures from the south. Metal working was principally in gold, silver, tin and lead, with some copper work known in what is now Michoacán. Gold was generally obtained in powder or pellet form in rivers and streams from
What Is to Be Done? (novel) based on his own ideas of moral responsibility. Vladimir Lenin, however, found it inspiring and named a 1902 pamphlet "What Is To Be Done?". Lenin is said to have read the book five times in one summer, and according to Professor Emeritus of Slavic and Comparative Literature at Stanford, Joseph Frank, 'Chernyshevsky's novel, far more than Marx's "Capital", supplied the emotional dynamic that eventually went to make the Russian Revolution.' The novel mentions (in the 4th dream of Vera Pavlovna) aluminium as the "metal of the future". In fact aluminium became widely used only starting with World War I (1914).