Verse 1: Arjun asks about the matter/energy (base material-prakriti) and causation(purush), object (kshetra) and subject (kshetragya). knowledge and knower.  These questions are really getting to the heart of the philosophy now.

Verse 2: Krishna says that this body is the base material and the consciousness is the causation.  Those who know this are the ones knowledgeable about subject and object.

Verse 3: Knowing that I am the awareness in every body is the real knowledge.  This is differentiating between our memory, our physical body which is different for each living entity from the soul (the causation) inside which is common between all living entity.  So while we have accumulated different responses and memories our inherent nature/causation is the same.

Verse 4-7: Krishna says that physical matter, energy and space (earth, water, air, fire and ether), sense of separate ego, intellect and the unmanifest element in the material nature, the ten sense and the mind and the five sense objects  desires, disdain, happiness distress, all this the object or the field of activity which is constantly modified by six transformations from birth to death.

Verse 8-12: 1) Humility, 2) sincerity, 3) non-violence, 4) tolerance, 5) simplicity, 6) service to teacher, 7) hygiene, 8) steadfastness, 9) self-control, 10) sacrifice of sense pleasures, 11) lack of self ego, 12) awareness of distress or elation caused by birth, death, old age and disease, 13) equipoise, 14) lack of excessive attachment to family and home, 15) consistent, 16) even minded to auspicious and inauspicious (isht-anisht), 17) preference for solitude, 18) away from mundane society, 19) devotional selfless service through yog of uniting selfish interests with universal interests, 20) constant meditation on the Ultimate Truth to achieve self-realization all these are the real knowledge and everything contrary to this a false knowledge. This is a list of 20 supreme qualities to cultivate.  If our education and upbringing focused on these attributes, we would create a harmonious, prosperous existence.

Verse 13-14: Krishna says he will describe the eternal truth which is everywhere and basis of everything.

Verse 15-17: The Ultimate Truth is aware of all senses, yet it is not impacted by them, it is unattached and yet is the basis of everything; beyond material nature yet the basis of the material nature.  It is inside all living entities and outside, it is stationary and mobile.  It is subatomic (sukshamtvat) and therefore far from comprehensible but all around us.  It is indivisible but appears divided in various living forms and manifests as creator, preserver and destroyer of everything.

Verse 18-19: The Ultimate Truth is in the heart of all but only realizable on wisdom gained through directly experiencing it. This is a description used by many a different life experiences.  Like becoming a parent, the way it feels can never be fully explained to someone who has not experienced it yet.  The full understanding of it comes through direct experience.

Verse 20: Know that both the material nature (matter and energy) and consciousness or primal cause (purush) are both without beginning.  All modifications and changes are only in the material nature as the consciousness is without change.

Verse 21: Material energy (prakriti) is responsible cause and effect in matter of creation.  Soul (purush) is responsible for experiencing happiness and distress.  This is a complex verse.  It states that all cause and effect is in the world of nature.  All experiential world is in the domain of soul (or the primal cause).  How does this square up with the soul (purush) being the sole and first cause?

Verse 22: The soul situated in material body experiences the three modes of material energy (sat, rajas, tamas).  Attachment to these three modes causes innumerable births  in various forms.

Verse 23-24: Within the body, beyond the individual consciousness (purush) is the Ultimate Consciousness which is the observer (updarshata), sanctioner (anumanta), preserver, experiencer (bhokta) and ultimate controller (maha ishvarah).  Understanding this in terms of Ultimate and individual consciousness, the three modes of material nature is the key to salvation.  So the ultimate consciousness is separately defined here as something different from the material energy and the individual consciousness.  

Verse 25-26: Some realize Ultimate Consciousness through meditating on the consciousness, others through study of matter and spirit (sankhya) and some others through the science of performing action in service of universal good. Some who don’t understand these methods, engage in worship simply by hearing from other learned people and also are liberated.

Verse 27: All living entities come into being by the interaction of subject and object (kshetra and kshetragya).

Verse 28-29: Anyone who perceives the ultimate consciousness residing in all equally perceives the truth. One who is able to see equality in others without degrading self has seen the truth.

Verse 30: Anyone who perceives that the activities are all being done in the material energy world such a person realizes that the Ultimate Consciousness is the non-doer.  It appears that we are moving in the zone of the individual consciousness not having any free will.

Verse 31: One who sees the unity of material nature in the diversity of the life forms, then the Ultimate Truth is attained.

Verse 32: the Ultimate Consciousness is without beginning, without change, without any material qualities and though residing in the body it is never impacted nor it does anything.

Verse 33: The space is everywhere but is not entangled with anything due to its subtlety  similarly the Ultimate Consciousness is everywhere but does not get entangled with any living form.

Verse 34-35: Just like sun energies the whole world, similarly the Ultimate Consciousness and the individual consciousness energize the objective world.

This chapter requires re-reading, thinking and meditation.  The concept of non-doer, yet controller is confusing.  As is the concept of soul that experiences everything but does not get entangled in it.  Also the concept of all cause and effect in material nature but the Ultimate Consciousness being the primal cause.  It appears that there are some statements which overlap or may even contradict.