  Much the same anti-teleological program underlies the ensuing prehistory of civilization (5.925–1457). Each cultural advance was prompted by nature, and only subsequently taken up and developed by human beings. Hence, it is implied, no divine intervention need be postulated as an explanatory tool. No Prometheus was needed to introduce fire, which rather was first brought to human attention by naturally kindled forest fires (5.1091–1101). Language emerged (5.1028–90) because people started to notice how their instinctive vocal responses to things, comparable to animal noises, could be put at the service of their intuitive desire to communicate (for which infants’ pre-linguistic pointing is cited as evidence). The same part of book 5 is rich in other cultural reconstructions, including the origin of friendship and justice in a primitive social contract (5.1011–27), and of conventional religion in early mankind’s misguided tendency to link visions of the gods, above all in dreams, to their desire to explain cosmic phenomena (5.1161–1240).