Thought is the basis of all creation. Everything was thought into existence. Even those physical things made by others were first born in thought before they became matter. The fourth principle is the principle of creativity. You are the creator of your experience, and it is your thinking that creates how you experience life.
Energy follows thought, and matter is energy condensed.
Therefore, everything in the world of matter is a result of thought. Your entire world, the world you see as being real and very alive, is energy that has been condensed into form by thought. It is as real as you wish to make it. Collectively, humanity and others species have created this reality, this dimension of existence, in order to create another unique experience. This is the experience you call Earth.