Śrīmad-Bhāgavatam · Text 11.2.38
Who is speaking and story frame
अविद्यमानोऽप्यवभाति हि द्वयो
ध्यातुर्धिया स्वप्नमनोरथौ यथा ।
तत् कर्मसङ्कल्पविकल्पकं मनो
बुधो निरुन्ध्यादभयं तत: स्यात् ॥ ३८ ॥
avidyamāno ’py avabhāti hi dvayo
dhyātur dhiyā svapna-manorathau yathā
tat karma-saṅkalpa-vikalpakaṁ mano
budho nirundhyād abhayaṁ tataḥ syāt
Although the duality of the material world does not ultimately exist, the conditioned soul experiences it as real under the influence of his own conditioned intelligence. This imaginary experience of a world separate from Kṛṣṇa can be compared to the acts of dreaming and desiring. When the conditioned soul dreams at night of something desirable or horrible, or when he daydreams of what he would like to have or avoid, he creates a reality that has no existence beyond his own imagination. The tendency of the mind is to accept and reject various activities based on sense gratification. Therefore an intelligent person should control the mind, restricting it from the illusion of seeing things separate from Kṛṣṇa, and when the mind is thus controlled he will experience actual fearlessness.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.