This understanding is key.
I think being able to see the notself vulnerabilities (in ourselves and others) is the way through to HD experimenting for most adults.
It cracks something open.
"Even though the defined parts in your chart are you and the undefined are not you in the sense that you take in energy from others via the open places in your chart, keep in mind that who you are overall is a synthesis of both.
You might have a defined throat and that certainly is who you are.
And if you have an open root that is where you take in the "Not Self" stress of other people's root energy, i.e. you can be pulled away from the truth of your defined throat though stress.
So in that sense, the open root can be who you are not because it is where elements that aren't you can be put inside you, like an open door for strangers. But that is definitely you.
You would be a person who is vulnerable to external stress that pulls you away from the truth of your defined throat."
Thanks, Oleksander