In Section 13 of Hadiqat al-Haqiqah, Sana'i explores the human soul and its various faculties. He differentiates between the five external senses, which become inactive and rest during sleep, and the internal faculties (such as memory, digestion, and distribution), which remain vigilant and active. Sana'i emphasizes that these inner faculties work tirelessly to maintain the body's health and well-being even when the conscious mind and external senses are suspended.