Thought externalizes itself. What we are depends entirely upon the images we hold before our mind's eye. Every time we think, we start a chain of causes, which will create conditions similar to the thoughts, which originated it. Every thought we hold in our consciousness for any length of time becomes impressed upon our subconscious mind and creates a pattern, which the mind weaves into our life or environment.
All power is from within and is therefore under our own control. When you can direct your thought processes, you can consciously apply them to any condition, for all that comes to us from the world without is what we've already imaged in the world within.