What does the power of thought mean?

James Allen notes that his little volume, the result of meditation and experience, is not intended as an exhaustive treatise on the much-written-upon subject of the power of thought. It is suggestive rather than explanatory—its object being to stimulate you to the discovery and perception of the truth that you yourself are the maker of yourself by virtue of the thoughts, which you choose and encourage—that mind is the Master Weaver, both of the inner garment of character and the outer garment of circumstance, and that as you may have hitherto have woven in ignorance and pain, you may now weave in enlightenment and happiness.

“They themselves are makers of themselves.”

—JAMES ALLEN