A horizontal perspective states the intrinsic properties of any physical system do not alone explain the behavior of the system. An environment surrounds all systems, and it is the causal interactions with their environment that provides systems with the extrinsic properties that determine their behavior. The illustration is how to understand the flock behavior of starlings. Extrinsic properties are distinct from relational properties. The suggestion is that mental properties, like sensory properties, are extrinsic properties of the nerve system being produced by environmental stimulations of sense organs. Apart from avoiding the problems with emergentism, such a view is in accord with Darwin's thesis that the environment plays a determining role in biological evolution through natural selection. As an evolutionary naturalist, one would expect that natural selection determined not only the anatomy and physiology of animals, but also their cognitive and mental features as well.