We have never learnt to keep our minds still as we sometimes keep our bodies still. It is by far the harder task but also the most rewarding one. Our thoughts continually titillate them and our desires periodically agitate them. What the inner resources of mind are, and what they can offer us, consequently remain unglimpsed and unknown. They are, in their totality, the Soul, and they offer us the kingdom of heaven.
-- Notebooks Category 4: Elementary Meditation > Chapter 1: Preparatory > # 47