An atom is the basic building block of cosmos. Perceived from senses point of view everything in cosmos appeared solid. In reality all was gaseous formation, clusters of atoms and molecules. Even human beings were simply clusters of atoms and molecules, pure gaseous formation.
The Prana energy that gave an atom its energy, its power to exist is atman as in Hinduism.
Behind every atom consisting of protons, neutrons and electrons exists Prana energy. In absence of atman, Prana energy no atom could exist (sustain) of its own.
If we a human being, clusters of atoms and molecules exist, behind us is an atman we called soul.
Atman (soul) is the primary driving force behind every living thing. In fact it is atman that manifests living forms to cleanse self of dross impurities within. As no atman could purify self of its own, it needs a medium a body to work out its karma.
For life to exist in cosmic system presence of atmans souls in cosmic system is an absolute must. In fact as per Advaita Vedanta philosophy propagated by Adi Shankaracharya other than world of atmans souls nothing existed in cosmos. The whole visible world was only an act of Maya (veil of ignorance).
This can be explained by looking in the mirror. The visible image in the mirror does not actually exist but we say the image exists. The image can exist only relatively and for this very reason Adi Shankaracharya says that the present cosmos exists only in thoughts of God Almighty.