One of the Four Pillars of life
"Building a foundation represents the fundamental work of spiritual development and human development." 
"All true spiritual development is rebuilding your relationship with Knowledge and allowing it to become the center of your life and the true guide of your life."
"Any activity that brings you into contact with Spirit—in other words, any activity that engages you with Knowledge—is, in essence, a spiritual practice and a form of spiritual development. Spiritual development has more to do with the motive than with the activity. And here we must question the fundamental elements of what motivates people to do things. If the motivation is for personal gain, then it cannot be said to be a form of spiritual development. If the activity is to control or dominate others or to escape from the real demands of life, then it cannot be said to be a form of spiritual development." 
"Spiritual development, said in the simplest of ways, is reclaiming your relationship with Knowledge—the immortal and eternal aspect of yourself that you have brought into this world." 
Spiritual development "involves spiritual practice of various kinds to enable your mind to think in harmony with Knowledge and to gain a greater perspective and understanding of the world and a thorough appreciation of your nature in relationship to the world." 
- Living The Way of Knowledge, Chapter 6: The Pillar of Spiritual Development