Everything that we can point to or name exists only for as long as other things come together in a certain way to support its existence. A table, for instance, is only a temporary meeting of an uncountable number of atoms working together for a certain period of time. Another example is the human body, which is a changing process that requires a constant supply of new material in the form of air, food, and water to sustain itself, and which is constantly expelling waste material. Even consciousness is not a static thing, but a perpetually changing stream of thoughts and impressions that also depends upon constant input of new material in the form of ideas and sensations.