Many people are confused about what it means when we talk about the outer world being a reflection of the inner self. It IS a complex concept, and it's one with several different layers of meaning. Here are three layers explained, each incrementally more advanced than the one before.
The Simple Version:
The first and simplest way to look at it is that whatever is within you is what you'll recognize most obviously in the people and circumstances around you. Whatever beauty and love you carry, whatever pain and aggression you carry, you will readily recognize that in others.
This perspective is built around the concept that we are most acutely aware of that which we most intimately know.
The Intermediate Version:
As you grow and evolve into the next, more advanced level, you’ll begin to understand the concept that you create your own reality. You do not simply create what you think about, you create what you ARE. So whatever is unhealed, sad or in grief – whatever you don’t like or cannot accept about yourself, will be re-created in the stories that show up in your life. (Sometimes we call these “patterns”.) You'll attract people that trigger your own unhealed places. They will trigger you because they’ll either dislike THEMSELVES in the same way you dislike yourself, or they’ll dislike YOU in that way. However it shows up, the idea is that it's an opportunity to look more closely at your own inner world with the ultimate goal of healing what's out of alignment with Love.
This perspective is built around the concept that the universe is a fractal. That is: whatever energy signature we carry will be repeated infinitely, again and again, until we change that vibration.
The Advanced Version:
At the most advanced level, you’ll come to know that in the deepest spiritual reality, there is only One Being in all of existence. Because there is only one of us here, “It” is creating all of this world we see, hear, feel, and perceive. “We”– the One – create seemingly billions of facets of our self. Each facet believes, in its small sphere of perception, that he or she is a distinct entity, separate from all the others. It is when you reach the highest levels of spiritual wisdom that you’ll realize that you can either choose to operate from this small, single little self, or you can remember the Oneness that WE are and harness the power of All That Is.
From the highest spiritual perspective, we know that the “others” are mirrors for us, because they actually ARE us. And at this level of spiritual attainment, the whole thing is uproariously entertaining — because we know that it's all an illusion, and that in reality, we are “all” just fine.
The world is a mirror into which I gaze — To see the Divine, My Beloved, My Self.