word mater, "mother", descends to English-speakers as matter and material. In Lucretius the Earth is a mother, Venus, to whom the poem is dedicated in the first few lines. She brought forth humankind by spontaneous generation. Having been given birth as a species, humans must grow to maturity by analogy with the individual. The different phases of their collective life are marked by the accumulation of customs to form material civilization: The earliest weapons were hands, nails and teeth. Next came stones and branches wrenched from trees, and fire and flame as soon as these were discovered. Then men learnt to use tough iron and copper. With copper they tilled the soil. With copper they whipped up the clashing waves of war, ... Then by slow degrees the iron sword came to the fore; the bronze sickle fell into disrepute; the ploughman began to cleave the earth with iron, ... Lucretius envisioned a pre-technological human that was "far tougher than the men of today ... They lived out their lives in the fashion of wild beasts roaming at large." The next stage was the use of huts, fire, clothing, language and the family. City-states, kings and citadels followed them. Lucretius supposes that the initial smelting of metal occurred accidentally in forest fires. The use of copper followed the use of stones and branches and preceded the use of iron. Early lithic analysis by Michele Mercati By the 16th century, a tradition had developed based on observational incidents, true or false, that the black objects found widely scattered in large quantities over Europe had fallen from the sky during thunderstorms and were therefore to be considered generated by lightning. They were so published by Konrad Gessner in De rerum fossilium, lapidum et gemmarum maxime figuris & similitudinibus at Zurich in 1565 and by many others less famous. The name ceraunia, "thunderstones", had been assigned. Ceraunia were collected by many persons over the centuries including Michele Mercati, Superintendent of the Vatican Botanical Garden in the late 16th century. He brought his collection of fossils and stones to the Vatican, where he studied them at leisure, compiling the results in a manuscript, which was published posthumously by the Vatican at Rome in 1717 as Metallotheca. Mercati was interested in Ceraunia cuneata, "wedge-shaped thunderstones", which seemed to him to be most like axes and arrowheads, which he now called ceraunia vulgaris, "folk thunderstones", distinguishing