What is Naturalism?

"Naturalism" is the dominant design style in ecological gardening, but what exactly is it? Is Naturalism just mimicry of nature, or does it allow for the designer to include aesthetic principles to please the human eye? Can it allow the gardener to enjoy favorite plants not indigenous to the area? Duncan Brine, co-proprietor with his wife Julia of design/build firm Garden Large explains how he has defined Naturalism to create some of the most celebrated new gardens of New York's Hudson River Valley.