Materialism can never offer a satisfactory explanation of the world. For every attempt at an explanation must begin with the formation of thoughts about the phenomena of the world. Materialism thus begins with the thought of matter or material processes. But, in doing so, it is already confronted by two different sets of facts: the material world, and the thoughts about it. The materialist seeks to make these latter intelligible by regarding them as purely material processes. He believes that thinking takes place in the brain, much in the same way that digestion takes place in the animal organs. 

Just as he attributes mechanical and organic effects to matter, so he credits matter in certain circumstances with the capacity to think. He overlooks that, in doing so, he is merely shifting the problem from one place to another. He ascribes the power of thinking to matter instead of to himself. And thus he is back again at his starting point. 

How does matter come to think about its own nature? Why is it not simply satisfied with itself and content just to exist? The materialist has turned his attention away from the definite subject, his own I, and has arrived at an image of something quite vague and indefinite. Here the old riddle meets him again. The materialistic conception cannot solve the problem; it can only shift it from one place to another.

Source: Rudolf Steiner – GA 4 – The Philosophy of Freedom: CHAPTER TWO: The Fundamental Desire for Knowledge