The Commens Dictionary

Quote from ‘Considerations concerning the Doctrine of Multitude’

In a […] general sense, a collection is simply an individual object whose being consists in the being of whatever objects there may be of a certain general description, these objects being called its members, so that every proposition concerning the collection as subject is equivalent to some relative proposition concerning the members as subjects. But this definition leaves it undetermined what the relation is to be between what is predicated, in any proposition, concerning the collection and the relative predicate concerning the members in the interpreting proposition.