Each is usually a monad.
"An Introduction to Chemical Science"
R.P. Williams
For, as he now uses the term, the very idea of a person is that of an essential, incommunicable monad, bounded by consciousness, and vitalized by self-active will; which being true, he might as well profess to hold that three units are yet one unit.
"Orthodoxy: Its Truths And Errors"
James Freeman Clarke
There may be in us an indestructible monad which feels and thinks, without our knowing anything at all of how that monad is made.
"A Philosophical Dictionary, Volume 5 (of 10) From "The Works of Voltaire - A Contemporary Version""
François-Marie Arouet (AKA Voltaire) Commentator: John Morley Tobias Smollett H.G. Leigh