Considered by many to be Iqbal's best book of poetry, Asrar-i Khudi is concerned with the philosophy of religion. In a letter to the poet Girani, Iqbal wrote that the ideas behind the verses had never been expressed before either in the East or in the West. R.A. Nicholson, who translated the Asrar as The Secrets of the Self, says it caught the attention of young Indian Muslims as soon as it was printed.

Iqbal wrote this in Persian because he felt the language was well-suited for the expression of these ideas.

The Asrar explains the importance of the ego and the clarification of the self. Iqbal believes the answers to essential questions regarding the ego are important in determining morality for both the society and the individual.