Krishna is the complete transcendental substance.  He is often compared to the sun of the spiritual realm, and the jivas are compared to the sun’s atomic particles of light.  Jivas are innumerable.  When it is said that they are individual parts of Krishna, it does not mean that they are like the pieces of stone that form a mountain.  Although innumerable, jiva portions emanate from Sri Krishna, Krishna is not diminished by this in the slightest.  For this reason, the Vedas have compared the jivas, in one respect, to sparks emanating from a fire.  In reality, no adequate comparison can be made.  No comparison—whether to sparks of a blazing fire, atomic particles within the rays of the sun, or gold produced from powerful mystic jewels—is completely appropriate.  The true nature of the jiva, is easily revealed in the heart, when the mundane, commonplace, and ordinary conception of these comparisons is given up.

Krishna is infinite spiritual substance, whereas the jivas are infinitesimal spiritual substance.  The oneness of Krishna and the jivas, lies in their spiritual nature, but they are undoubtedly different as well, because their natures are complete and incomplete respectively. 

• Krishna is the eternal Lord of the jivas, and the jivas are Krishna’s eternal servants. This interrelationship is natural. 
• Krishna is the attractor, and the jivas are attracted.
• Krishna is the supreme ruler, and the jivas are ruled.
• Krishna is the observer, and the jivas are observed.
• Krishna is the complete whole, and the jivas are parts and parcel, poor and insignificant.
• Krishna is the possessor of all potency (energy), and the jivas are devoid of potency.
• Therefore, the eternal true nature or dharma of the jiva, is eternal service and obedience to Krishna.
• Krishna is endowed with unlimited potencies (energies).

Krishna’s complete potency is perceived in the manifestation of the spiritual world. 

Similarly, His marginal potency is observed in the manifestation of the jivas.  This marginal energy acts in assembling the finite world.  The action of the marginal potency is to create an entity which exists between the animate objects, and inanimate objects, and which can maintain a relationship with both the spiritual, and material worlds.  Purely transcendental entities, are by nature, quite the opposite of inanimate objects, and therefore have no connection whatsoever with them.  Although the jiva is an animate spiritual particle, he is capable of a relationship with inanimate matter.

The jiva’s nature is spiritual, but still, its composition is such that it can become controlled by the inert nature of the material world.  Therefore, the conditioned jiva (conditioned soul) is not beyond all connection with matter, unlike the jivas in the spiritual domain.  Nonetheless, the jiva is distinct from dull matter, because of its animate, spiritual nature.  Since the jiva is by nature different from both the purely spiritual entities, and dull matter, the jiva is classified as a separate principle.  Therefore, the eternal distinction between Bhagavan and the jiva must be accepted.

Bhagavan is the supreme ruler of maya (His external potency which creates the material world and bewilderment), which is under His full control.  On the other hand, the jiva may be controlled by maya, under certain circumstances, for it is subject to its influence. 

Maya—illusion; an energy of Krishna’s which deludes the living entity into forgetfulness of the Supreme Lord. That which is not, unreality, deception, forgetfulness, material illusion.

Under illusion a man thinks he can be happy in this temporary material world. The nature of the material world is that the more a man tries to exploit the material situation, the more he is bound by maya’s complexities; This is a Sanskrit term of many meanings. It may mean energy; yoga-maya is the spiritual energy sustaining the transcendental manifestation of the spiritual Vaikuntha world, while the reflection, maha-maya, is the energy of the material world. The Lord’s twofold maya bewilders the jéva, hence maya also means bewilderment or illusion. Transcendental bewilderment is in love, by which the devotee sees God as his master, friend, dependent or amorous beloved. The material bewilderment of the living entity begins with his attraction to the glare of the brahmajyoti. That attraction leads to his entanglement in the “modes of material nature”. According to Bhaktisiddhanta Sarasvati Thakura, maya also means that which can be measured. This is the feature of Lord Krishna’s prakrti that captures the minds of scientific materialists.

Modes of nature—There are three gunas, or modes of material nature: goodness (sattva-guna), passion (rajo-guna) and ignorance (tamo-guna). They make possible our mental, emotional and physical experiences of the universe. Without the influence of the modes, thought, value judgement and action are impossible for the conditioned soul.

The English word mode, as used by Srila Prabhupada in his translations of Vedic literature, best conveys the sense of the Sanskrit term guna (material quality). Mode comes from the Latin modus, and it has a special application in European philosophy. Modus means measure. It is used to distinguish between two aspects of material nature: that which is immeasurable (called natura naturans, the creative nature) and that which seems measurable (called natura naturata, the created nature). Creative nature is a single divine substance that manifests, through modes, the created nature, the material world of physical and mental variety. Being immeasurable (in other words, without modes), creative nature cannot be humanly perceived.

Created nature (with modes) seems measurable, hence we do perceive it. Modus also means a manner of activity. When creative nature acts, it assumes characteristic modes of behavior: creation, maintainance and destruction. Bhagavad-gita (14.3-5) presents a similar twofold description of material nature as mahat yoni, the source of birth, and as guna prakåti, that which acts wonderfully through modes. Material nature as the source of birth is also termed mahad-brahman, the great or immeasurable Brahman. Mahad-brahman is nature as the divine creative substance, which is the material cause of everything.
Material cause is a term common to both European philosophy (as causa materialis) and Vedanta philosophy (as upadana karana). It means the source of ingredients that make up creation. We get an example of a material cause from the Sanskrit word yoni, which literally means womb. The mother’s womb provides the ingredients for the formation of the embryo. Similarly, the immeasurable creative nature provides the ingredients for the formation of the material world in which we live, the seemingly measurable created nature. The clarity of this example forces a question: what about the father, who must impregnate the womb first before it can act as the material cause? This question is answered by Krishna, the speaker of the Bhagavad-gita, in verse 14.4: “I am the seed-giving father”. In Vedänta philosophy, this factor of causation is termed nimitta-matram (the remote cause).

It is important to note that by presenting creation as the result of the union of two causes (the material and the remote), the Bhagavad-gita rejects the philosophy of Deus sive natura, the identity of God and nature. In short, though creative nature may be accepted as the direct cause of creation, it is not the self-sufficient cause of creation. The seed with which Krishna impregnates the womb of creative nature is comprised of sarva-bhutänam, all living entities (Bhagavad-gita . 14.3). And Bhagavad-gita . 14.5 explains that when Krishna puts the souls into the womb of material nature, their consciousness is conditioned by three modes, or tri-guna. The modes are three measures of interaction between conscious spirit and unconscious matter. The modes may be compared to the three primary colors, yellow, red and blue, and consciousness may be compared to clear light.

The conditioning (nibhadnanti: they do condition) of consciousness upon its entry into the womb of material nature is comparable to the coloration of light upon its passing through a prism. The color yellow symbolizes sattva-guna, the mode of goodness. This mode is pure, illuminating, and sinless. Goodness conditions the soul with the sense of happiness and knowledge. The color red symbolizes the rajo-guna, the mode of passion, full of longings and desires. By the influence of passion the soul engages in works of material accomplishment. The color blue symbolizes tamo-guna, the mode of ignorance, which binds the soul to madness, indolence and sleep.

As the three primary colors combine to produce a vast spectrum of hues, so the three modes combine to produce the vast spectrum of states of conditioned consciousness that encompasses all living entities within the universe.

Hence, these three principles—Bhagavan, the jiva, and maya—are real and eternal.  Of these three, Bhagavan is the supreme eternal principle, and is the foundation of the other principles.  The following statement of Sri Katha Upanisad (2.2.13) confirms this, 

“He is the supreme eternal amongst all eternals; and the fundamental sentient being among all sentient beings”.

The jiva is by nature both an eternal servant of Krishna, and a representation of His marginal potency.  This demonstrates that the jiva is distinct from Bhagavan, yet at the same time is not separate from Him.  The jiva is, therefore, a manifestation that is both different and non-different.  The jiva is subject to domination by maya, whereas Bhagavan is the controller of maya.  Herein lays an eternal distinction between the jiva and Bhagavan.  On the other hand, the jiva is by its constitutional nature a transcendental entity, and Bhagavan is by nature a transcendental entity as well.  Moreover, the jiva is a special potency (energy) of Bhagavan.  Herein lays the eternal non-distinction between these two.  Where eternal distinction and non-distinction are found at the same time, eternal distinction takes prominence.