In Chapter 21, Poem 18 of Mokhtar Nameh, Attar explores the theme of absolute determinism and the eternal decree of destiny. He argues that since all events have already been written by the 'pen' of destiny, experiencing feverish anxiety, torment, or engaging in ascetic practices like fasting and sleeplessness are ultimately futile. The poem emphasizes accepting the unchangeable nature of the divine decree rather than struggling against it.