The "Naturalis Historia" is one of the largest works to have survived from the Roman Empire to the modern day. It claims to cover the entire field of ancient knowledge, based on the best authorities available to Pliny. He claims to be the only Roman ever to have undertaken such a work. It includes the fields of botany, zoology, astronomy, geology and mineralogy as well as the exploitation of those resources. It remains a standard work for the Roman period and the advances in technology and understanding of natural phenomena at the time. 