This profound statement encapsulates the fundamental Stoic principle that our subjective experience of reality is entirely shaped by our thoughts and judgments, not by external circumstances. The external world remains neutral - events simply happen - but it is the color, texture, and meaning we give them through our thinking that creates our personal world of happiness or misery. Marcus Aurelius understood that we live not in the world as it is, but in the world as we perceive it to be. This places immense power in our hands: by changing our thinking patterns, we can transform our entire experience of life. It's both liberating and sobering - we are the architects of our own mental reality.