Subjective idealism is the correct way to view the world. Because reality is built in the mind, one can use various techniques to loosen one's inhibitions and bring change to one's internal model of reality. As one can never directly observe "objective reality", any "subjective" changes that occur will appear to one as changes in "objective reality". All magickal systems are symbolic psychological models, and all occult praxes are psychological tricks to create these "subjective" changes.
What the materialists don't want you to know, however, is that scientific positivism exists only within their own minds, and is itself a magickal system of representing psychological realities. The only true reality that you can ever prove to exist is your immediate sense reality, created by your psychology. This is the key to all occult knowledge.