Moreno wrote in Who Shall Survive? (1934, page xxx; revised edition 1953) the following that are divided into several parts for your contemplation:
"Four aspects of group psychotherapy struck me already then; they became later the cornerstones of all forms of group psychotherapy:
1) the autonomy of the group;
2) that there is a group structure and the need for knowing more about it, group diagnosis as a preliminary to group psychotherapy;
3) the problem of collectivity; prostitution represents a collective order with patterns of behavior, roles and mores which colors the situation independent from the private participants and the local group;
4) the problem of the anonymity. When a client is treated within the framework of individual therapy, he is alone with the doctor, his ego is the only focus, he has a name, his psyche is highly valued private property. But in group psychotherapy there is a tendency towards anonymity of membership, the boundaries between the egos weaken, the group as a whole becomes the important thing."
Who Shall Survive? is available on line at asgpp.org. Click on "RESOURCES". The following screen has a title, "Books". There you will find Who Shall Survive? and many other titles.