In the final part of the "Ethics", his concern with the meaning of "true blessedness", and his explanation of how emotions must be detached from external causes in order to master them, foreshadow psychological techniques developed in the 1900s. His concept of three types of knowledge—opinion, reason, intuition—and his assertion that intuitive knowledge provides the greatest satisfaction of mind, led to his proposition that the more we are conscious of ourselves and Nature/Universe, the more perfect and blessed we are (in reality) and that only intuitive knowledge is eternal.