SB 7.7.26
ebhis tri-varnaih paryastair
buddhi-bhedaih kriyodbhavaih
svarupam atmano budhyed
gandhair vayum ivanvayat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As one can understand the presence of the air by the aromas it carries, so, under the guidance of the Supreme Personality of Godhead, one can understand the living soul by these three divisions of intelligence. These three divisions, however, are not the soul; they are constituted of the three modes and are born of activities.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As already explained, there are three states to our existence, namely wakefulness, dreaming and deep sleep. In all three states, we have different experiences. Thus the soul is the observer of these three states. Actually, the activities of the body are not the activities of the soul. The soul is different from the body. Just as aromas are distinct from the material vehicle in which they are carried, the soul is unattached to material activities. This analysis can be considered by a person who is fully under the shelter of the lotus feet of the Supreme Lord. This is confirmed by the Vedic injunction yasmin vijñate sarvam evam vijñatam bhavati. If one can understand the Supreme Personality of Godhead, one can automatically understand everything else. Because of not taking shelter of the Lord’s lotus feet, even great scholars, scientists, philosophers and religionists are always bewildered. This is confirmed in Srimad-Bhagavatam (10.2.32):
ye ’nye ’ravindaksa vimukta-maninas
tvayy asta-bhavad avisuddha-buddhayah
Even though one may artificially think himself liberated from material contamination, if he has not taken shelter of the Lord’s lotus feet his intelligence is polluted. As stated in Bhagavad-gita (3.42):
indriyani parany ahur
indriyebhyah param manah
manasas tu para buddhir
yo buddheh paratas tu sah
Above the senses is the mind, above the mind is the intelligence, and above the intelligence is the soul. Ultimately, when one’s intelligence becomes clear through devotional service, one is situated in buddhi-yoga. This also is explained in Bhagavad-gita (dadami buddhi-yogam tam yena mam upayanti te). When devotional service develops and one’s intelligence becomes clear, one can use his intelligence to return home, back to Godhead.