A system is an entity which maintains its existence
through the mutual interaction of its parts.
The key emphasis here is one of "mutual interaction,"
in that something is occurring between the parts, over time,
which maintains the system. A system is different than a heap
or a collection, mostly.
Associated with the idea of system is a principle called
emergence. From the mutual interaction of the parts of a system
there arise characteristics which can not be found as characteristic
of any of the individual parts.
One has to study the system to get a true understanding
of wetness. Studying the parts will not provide an appropriate