Chapter 3 · The Yoga of Action · Krishna said
Bhagavad Gita 3.38 — Knowledge hidden by desire
धूमेनाव्रियते वह्निर्यथादर्शो मलेन च। यथोल्बेनावृतो गर्भस्तथा तेनेदमावृतम् ॥
dhūmenāvriyate vahniryathādarśo malena ca | yatholbenāvṛto garbhastathā tenedamāvṛtam ||
Meaning
As fire is covered by smoke, a mirror by dust and an unborn child by the womb, so knowledge is covered by desire.