Bhagavad Gita: Chapter 15, Verse 8

शरीरं यदवाप्नोति यच्चाप्युत्क्रामतीश्वर: |
गृहीत्वैतानि संयाति वायुर्गन्धानिवाशयात् || 8||

śharīraṁ yad avāpnoti yach chāpy utkrāmatīśhvaraḥ
gṛihītvaitāni sanyāti vāyur gandhān ivāśhayāt

śharīramthe body; yatas; avāpnoticarries; yatas; cha apialso; utkrāmatileaves; īśhvaraḥthe Lord of the material body, the embodied soul; gṛihītvātaking; etānithese; sanyātigoes away; vāyuḥthe air; gandhānfragrance; ivalike; āśhayātfrom seats


BG 15.8: As the air carries fragrance from place to place, so does the embodied soul carry the mind and senses with it, when it leaves an old body and enters a new one.


The phenomenon of transmigration of the soul is explained here.  The example given is of the breeze transporting the fragrance of flowers from one place to another.  Likewise, when the soul departs at the time of death, it discards the gross body.  But it carries with it the subtle and causal bodies, which include the mind and senses.  (The three kinds of bodies were described in detail in verse 2.28)

While the soul gets a new body in every life, the mind continues journeying with it from past lifetimes.  This explains why even people who are blind from birth can see dreams.  Usually dreams are a result of the distortion of our visions and thoughts during the waking state that get disjointed and connected while asleep.  For example, let us say that someone sees a bird flying and thinks, “If I were a bird how nice it would be!”  In the dream, he finds himself flying in the human body itself.  That is because the thoughts and visions of the waking state became distorted and linked in the dream state.  However, a person who is blind from birth has never seen any forms and shapes, and yet that person can see dreams because impressions of the waking state are stored in the subconscious of the mind from endless past lifetimes.  Having explained that the soul takes the mind and senses with it when it departs from the body, Shree Krishna next explains what it does with these.