The idea came to me as one switches on a light, one day  when by chance there fell into my hands an old dusty diagram,  the work of some unknown predecessor of mine. Since a chemist does not think, indeed does not live without models, I idly went about representing them for myself, drawing on paper the long chains of silicon, oxygen, iron and magnesium, with the nickel caught between their links and I did not feel much different from the remote hunter of Altamira who painted an antilope on the rock wall so that the next dayís hunt would be lucky.

Primo Levi, “The Periodic Table”, 1975