These are the seven shepherds (Abraham, Isaac, Jacob, Moses, Aaron, Joseph, David) and mark the availability of different pathways to the Divine.
There is a division of essence.
There are people who are more inclined to the soul of Abraham and others who favor of the line of Isaac.
Each receives a certain quality from a source that determines the structure of his personality.
The greater the receptivity, the more one is able to get from any one branch of the menorah.”
From The Candle of God, “Implications of the Menorah,” p.329-330, by Rabbi Adin Steinsaltz