What is Mind?

Infinite Universal Consciousness is also called "Brahmn". In this Infinite Universal Consciousness this entire universe is pervaded. When a Spark of this Universal Consciousness is conditioned by and undergoes modification by mixing with Nature Elements or with the external body, then this conditioned Consciousness is called MIND. In such a situation Consciousness forgets it's true nature that it's a part of & of the nature of that Infinite Universal Consciousness. Such a conditioned consciousness is also called Jiva.

This Jiva / Mind after forgetting it's true nature (being part of & of the nature of that Infinite Universal Consciousness), inherits a body & makes appearance in this world. Such a conditioned soul / Jiva takes birth in different bodies & moves from one body to other body after death. Such a journey of soul / Jiva goes forever until it sees the truth again.

But Infinite Universal Consciousness, called "Brahmn" is independent of all these & pervades this whole universe, beyond this Jiva & beyond this body.

It is due to our Ignorance only (after forgetting the Infinite Universal Consciousness called "Brahmn") that this universe exists. Once we know ourselves to be a part & parcel of that Infinite Universal Consciousness, then this illusion of universe disappears & you become one with the "Brahmn".

Below are some verses from Bhagwat Gita which illustrates the same:

"mamaivamso jiva-loke
jiva-bhutah sanatanah
manah-sasthanindriyani
prakriti-sthani karshati" (Bhagwat Gita: Chapter Fifteen verse 7)

"Sri Krishna said: O Arjuna, The living entities in this conditioned world are My eternal fragmental parts. Due to conditioned life, they are struggling very hard with the six senses, which include the mind."

"sariram yad avapnoti
yac chapy utkramatishvarah
grhitvaitani samyati
vayur gandhan ivasayat" (Bhagwat Gita: Chapter Fifteen verse 8)

"Sri Krishna said: O Arjuna, The living entity in the material world carries his different conceptions of life from one body to another as the air carries aromas. Thus he takes one kind of body and again quits it to take another."

"srotram chaksuh sparshanam cha
rasanam ghranam eva cha
adhisthaya manas chayam
visayan upasevate" (Bhagwat Gita: Chapter Fifteen verse 9)

"Sri Krishna said: O Arjuna, The living entity, thus taking another gross body, obtains a certain type of ear, eye, tongue, nose and sense of touch, which are grouped about the mind. He thus enjoys a particular set of sense objects."

"utkramantam sthitam vapi
bhunjanam va gunanvitam
vimudha nanupasyanti
pasyanti jnana-chaksusah" (Bhagwat Gita: Chapter Fifteen verse 10)

"Sri Krishna said: O Arjuna, The foolish cannot understand how a living entity can quit his body, nor can they understand what sort of body he enjoys under the spell of the modes of nature. But one whose eyes are trained in knowledge can see all this."

"yatanto yoginas chainam
pasyanty atmany avasthitam
yatanto ’py akritatmano
nainam pasyanty acetasah" (Bhagwat Gita: Chapter Fifteen verse 11)

"Sri Krishna said: O Arjuna, The endeavoring transcendentalists, who are situated in self-realization, can see all this clearly. But those whose minds are not developed and who are not situated in self-realization cannot see what is taking place, though they may try to."

"sarvasya chaham hridi sannivisto
mattah smritir jnanam apohanam cha
vedais cha sarvair aham eva vedyo
vedanta-krd veda-vid eva chaham" (Bhagwat Gita: Chapter Fifteen verse 15)

"Sri Krishna said: O Arjuna, I am seated in everyone’s heart, and from Me come remembrance, knowledge and forgetfulness. By all the Vedas, I am to be known. Indeed, I am the compiler of Vedanta, and I am the knower of the Vedas."

"dvav imau purushau loke
ksharas chakshara eva cha
ksharah sarvani bhutani
kuta-stho ’kshara uchyate" (Bhagwat Gita: Chapter Fifteen verse 16)

"Sri Krishna said: O Arjuna, There are two classes of beings, the fallible and the infallible. In the material world every living entity is fallible, and in the spiritual world every living entity is called infallible."

"uttamah purushas tv anyah
paramatmety udahrtah
yo loka-trayam avisya
bibharty avyaya ishvarah" (Bhagwat Gita: Chapter Fifteen verse 17)

"Sri Krishna said: O Arjuna, Besides these two, there is the greatest living personality, the God Soul, the imperishable Lord Himself, who has entered the three worlds and is maintaining them."