In the opening chapter of Kashf al-Mahjub, Hujwiri affirms the religious obligation to seek knowledge, citing the Prophetic sayings that seeking knowledge is a duty upon every Muslim and that one should seek it even as far as China. He then qualifies this claim: because knowledge is vast and life is short, mastering every science is not individually obligatory. Sciences such as astronomy, medicine, and arithmetic are required only to the extent that they serve religious duty — astronomy for determining times of night, medicine for treating illness, and arithmetic for calculating inheritance shares and prescribed waiting periods. The obligatory measure of knowledge is therefore whatever makes correct religious practice possible, and Hujwiri censures the pursuit of learning that yields no spiritual benefit.