In a recent paper1 I argued that observation can be thought of as the result of a properly composed and functioning observation system. In brief, such a system must be composed of a source object and one or more devices which interact with a receptor. If we think of observation as the result of interaction among components are differing functions, we can approach the problem of describing human sense perception as that of describing one type of observation, differentiated from other types by the organic and species specific nature of the receptor devices. Receptor devices are typed by their specific range of sensitivity, which is best thought of as a limit on the type of devices with which the receiver can interact. One consequence of this view is that observation can be achieved in all sorts of ways by all sorts of organic and non-organic systems as long as they satisfy functional conditions.