Q: Why was the science of spiritual wayfaring (ʿilm al-sulūk) called the science of the secret (ʿilm al-sirr)?

The science of سلوك (spiritual wayfaring) is the knowledge of the self and its related emotional states. It is also known as the science of ethics (أخلاق) and Sufism (تصوف). Ibn al-Qayyim expounded on it extensively in "Sharh al-Manazil" and "Safar al-Hijratayn." Naming it the "science of secrets" is an error committed by some Sufis, who claim that certain sciences are only suitable for a specific category of people.