Full Idea
The general name 'monad' or 'entelechy' may suffice for those substances which have nothing but perception and appetition; the name 'souls' may be reserved for those having perception that is more distinct and accompanied by memory.
Gist of Idea
A 'monad' has basic perception and appetite; a 'soul' has distinct perception and memory
Source
Gottfried Leibniz (Monadology [1716], §19)
Book Reference
Leibniz,Gottfried: 'Monadology and Other Philosophical Essays', ed/tr. Schrecker,P [Bobbs-Merrill 1965], p.150
A Reaction
It is basic to the study of Leibniz that you don't think monads are full-blown consciousnesses. He isn't really a panpsychist, because the level of mental activity is so minimal. There seem to be degrees of monadhood.