Atomic theory has to do with everything we see in reality being made of small things we cannot see - atoms. The name "
atom" comes from the Greek and means, literally, that which cannot be "
cut". Today, theories of physics and the results of experiments show that atoms are made up of smaller parts.
This means that everything we see in reality is made up of small things we cannot see - but those "
uncuttable parts" may be smaller than what we today call "
atoms". At least that is the physical reality or physics explanation.
More interesting than physical things are the abstract ideas or plans (e.g., in the mind of God) that are used to create what we see. Such ideas are not directly visible. That is, the distinction of "
it" from "
bit".