« The whole sum of the surrounding external conditions within which an organism, a community or an object exists. The term is often used in a limited way in geography; e.g, the natural e. meaning either the non-cultural and no-social e., or the landscape before the Man came. The geographical e. means the factors of the e. whose relationships are considered in terms of spatial location. The physical e. includes all phenomena apart from Man and the things he creates, while the nonhuman e. everything not in a social system, whether made by Man or not. These are slightly different, and unqualified use of the term can be misleading. »

Francis John Monkhouse, A Dictionary of Geography, Londres : Taylor & Francis, 2017, p.124

« The environment of animals and men is what they perceive. The environment is not the same as the physical world, if one means by that the world described by physics. The observer and his environment are complementary. So are the set of observers and their common environment. The components and events of the environment fall into natural units. These units are nested. They should not be confused with the metric units of space and time. The environment persists in some respects and changes in other respects. »

James J. Gibson, The Ecological Approach to Visual Perception, Londres : Psychologic Press, 2015, p.11