This book contains extracts from letters written by Sri Aurobindo to his disciples. In the letters he explains his teaching and method of spiritual practice and addresses some of the difficulties and problems that the disciples were encountering. The extracts are arranged in sections that deal with subjects such as the goal and aim of the Yoga, the planes and parts of the being, the principle and practice of surrender and opening to the influence of the Divine, and the value of work in bringing the results of one's inner progress to the external nature and life.