Palindrome (; "again") and ' (; "way, direction"). Palindromes date back at least to 79 AD, as a palindrome was found as a graffito at Herculaneum, a city buried by ash in that year. This palindrome, called the Sator Square, consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas" ("The sower Arepo holds with effort the wheels"). It is remarkable for the fact that the first letters of each word form the first word, the second letters form the second word, and so forth. Hence, it can be arranged into a word square that reads in four different
Precautionary principle that preventing innovation from coming to market means that only current technology may be used, and current technology itself may cause harm or leave needs unmet; there is a risk of causing harm by blocking innovation. As Michael Crichton wrote in his novel "State of Fear": "The 'precautionary principle', properly applied, forbids the precautionary principle." For example, forbidding nuclear power plants based on concerns about risk means continuing to rely on power plants that burn fossil fuels, which continue to release greenhouse gases. In another example, the Hazardous Air Pollutant provisions in the 1990 amendments to the US Clean Air