"Do unto others as you would have them do unto you," is the underlying tenet of all the world's major religions and philosophies. The statement and all its variations is considered The Golden Rule. Yet, metaphysically speaking, if a person does not understand who they really are, how they treat others will be a direct reflection of how they regard themselves.
In metaphysical and spiritual terms, "knowing oneself" is knowing how The Creator/Source sees us. If love is the perfect representation of Source, then we and all of creation are perfect love according to Source. The consciousness of The Creator is manifest in all of creation and is perfect.
One of the challenges of life on Earth is remembering who we are. As we journey back to the origin of our Source, we encounter many illusions through the filter of the physical mind. Many fearful concepts of life and death distract our ability to trust that we are loved. We see our lives, on the surface, as threatening. From this "surface" perspective we allow others to direct our lives; people who are not yet qualified for this job.
Why is it that we allow people to lead us who have no discernment? It is because we have no discernment. The people we choose to lead us are reflections of our own levels of consciousness and it all comes back to Self-Love. If we know the nature of The Creator/Source, we know who we are--individual expressions of Love. We can only treat others how we treat ourselves.
As each one of us is able to "know" our origin, it will be impossible not to love ourselves. As we love ourselves, we can begin to love others. Even if we just have the desire to love ourselves, but don't know how; that intent will lead us out of our self-imposed bondage. Ultimately, we know truth by the fruits that are harvested.