At the world level, we assess our ability, strength, or power before embarking upon a new venture. At the higher level, the value of knowledge is tested by its power to purify and ennoble one's life, and by its application to the evolution of one's character. This book helps to understand better one's intellectual nature in order to cultivate the good in it, and allow the One Self to be the Knower. The oneness of the Self is not easy to comprehend, but the author asserts that 'those who would fulfil the maxim "Know thyself" must not shrink from a little mental exertion, nor must expect mental food to drop ready-cooked from the sky into a lazily-opened mouth'.
Once we realize the potential of thought power, we must use it for the good of others, with great awareness and discrimination, in order to help along spiritual evolution. 'Choose well; your choice is brief, and yet endless.'