Never saw it in print, but I have a theory about the source of a great deal of anxiety. I believe it's often caused because we are hearing two voice--the two that were often in conflict in our childhood or youth. We hear our mother's voice, perhaps louder for most people than our father's. Yet his also rings in our ears, quietly, throughout our lives.
If either parent wasn't around for some reason, there's usually at least one other voice that is strong. Not necessarily a voice of strength for us, but a voice that dominates so much of our thinking and behavior. No doubt much more often than we recognize.
There are other voices that may even over-ride those those of our parents. As we mature. Voices of grandparents or other family members, teachers or church leaders, or the voices of peers. The voices of spouses loom huge for most of us, as well.
Those voices do not have to be positive. Hopefully more are positive than negative, though.
Finding our own voice and making it say the positive things or to speak words of truth and reality--that's what helps healthy people mature beautifully.
Yet we have to be very careful that we are checking out our voice at times with wise people who can provide some guidance. That's something we all need--sort of like having parents that we learn to choose wisely as we mature.