in his 1973 book "behind the mirror: a search for a natural history of human knowledge", lorenz considers an old philosophical question: do our senses actually tell us about the world as it is? or do they only give us an illusion? lorenz' answer comes from evolutionary biology. only things that help a species to survive and reproduce are kept. anything that does not benefit a species is quickly removed through the process of natural selection. lorenz argued that if our senses gave us wrong information about our environment, humanity would soon be extinct. therefore we can be sure that our senses give us correct information, for otherwise we would not be here to be deceived.