The soul is a "particle of consciousness". What does it mean?

The soul is beyond measurement (ayam sankhyātīto), being a particle of consciousness (cit-kaṇaḥ). What does it mean? What exactly is the soul?

The soul is not a material particle, and therefore it can't be found by experimental means. Whatever is the smallest particle one is capable of measuring using whatever instruments one has at his disposal, the soul is still smaller. With the naked eye, the tip of a hair is the smallest particle one can see. However, if one has an electron microscope, he will see that ultimately the tip of the hair is a single atom. In both cases, the soul is still smaller, and thus always escapes the understanding of the materialist.

In the Bhagavad-gītā 2.17, Prabhupada mentions that "When the upper point of a hair is divided into one hundred parts and again each of such parts is further divided into one hundred parts, each such part is the measurement of the dimension of the spirit soul."

This is a reference to the Śvetāśvatara Upaniṣad (5.9): keśāgra-śata-bhāgasya, śatāmśaḥ sādṛśātmakaḥ, jīvaḥ sūkṣma-svarūpo ’yam, sankhyātīto hi cit-kaṇaḥ.

The first two lines, keśāgra-śata-bhāgasya śatāmśaḥ sādṛśātmakaḥ describe that when the tip of the hair (keśāgra) is divided into one hundred parts (śata-bhāgasya) and each part is again divided into one hundred parts (śatāmśaḥ), each part is similar in size to measurement of the soul. The verse then continues, explaining that in reality, the soul has no material form, being extremely subtle (jīvaḥ sūkṣma-svarūpo). This soul is beyond measurement (ayam sankhyātīto), being a particle of consciousness (cit-kaṇaḥ). This last word is especially significant for understanding the nature of the soul.

In the 15th chapter of the Bhagavad-gītā, Krsna explains the material world as a gigantic tree that is upside down. In other words, the tree of the material world is like a reflection of the real three in the spiritual world. A reflection is not false, it exists, but it is just an ephemeral projection of the real object. Due to the properties of light, a reflection is also always inverted or upside down. In Bg 2.16, Krsna defines everything that is material as asat, and everything spiritual as sat. All material objects are just a reflection of some real object in the spiritual world. Everything that exists here also exists there in its original, eternal form.

In the 3rd canto of Srimad Bhagavatam (3.27), Lord Kapila goes deep into this example, giving the example of the sun reflected in a pot of water in a dark room, and from there illuminating the walls of the room to explain both the presence of the Lord and the soul in this material world. The Lord never enters directly in contact with the material nature, but at the same time, He is present everywhere as Paramātmā. Mahā-Vishnu is like the sun, Garbhodakaśāyī Vishnu is like the reflection of the pot of water, and Paramātmā is like the reflection on the walls. In this way, the Lord becomes present in the material world, while simultaneously away from it. This same example is mentioned in the Vedanta-sutra to explain the same point.

What about the soul? The soul is just like the Lord (tat tvam asi). The Lord is like the sun, and the soul is like a ray of the sun or like a small sun. Sometimes it is also described as the Lord being like the moon and the souls being like stars, conveying the same idea. They are qualitatively one, but quantitatively distinct.

The infinite Lord can simultaneously permeate all material universes, while the infinitesimal soul can permeate just a single material body. Just like the Lord doesn't come in contact with the material energy, the soul also doesn't, although the consciousness of the soul somehow becomes entrapped here. Lord Kapila explains this point on SB 3.27.13: evam trivṛd-ahankāro, bhūtendriya-manomayaiḥ, svābhāsair lakṣito ’nena, sad-ābhāsena satya-dṛk.

There are two meanings in this verse. One is that the soul is reflected in the false ego, and then in the body, senses, and mind, and another is that the Supreme Brahman, the Lord, is reflected in the material elements and is thus present everywhere. Prabhupada translates it as "The self-realized soul is thus reflected first in the threefold ego and then in the body, senses and mind." and then explains also the other meaning in his purport. A pure devotee can see the Lord present everywhere by His reflection in the material energy, understanding that everything should be used in His service.

Just as the Lord is present in the material world as a reflection, the pure devotee can see himself also present as a reflection. The consciousness of the soul is first reflected in the three divisions of the false ego (in goodness, passion, and ignorance) and from there permeates the body, senses, and mind, just like the sun first reflected in the water and then in the walls. In this way, the big sun permeates all material universes, while the small sun permeates just a particular body, but both are eternally situated in the sky.

Lord Kapila also explains (on SB 3.26) that material consciousness is created at the beginning of the material creation as a reflection of the original, spiritual consciousness of the soul. In this way, the soul who is transcendental, always pure and immovable, becomes manifested inside the material creation as a reflection, just like the Lord. This reflection is then covered by the seven coverings (the false ego, mind, intelligence, senses, vital airs, gross body, and the organs of the senses). This explains the idea of the soul being a particle of consciousness (cit-kaṇaḥ) from Śvetāśvatara Upaniṣad 5.9. Extra confirmation is given in SB 2.9.1, where Sukadeva Goswami mentions that "there is no meaning to the relationship of the pure soul in pure consciousness with the material body. That relationship is just like a dreamer’s seeing his own body working."

Any question? Post it in the comments, I will do my best to answer. If you think this post can be useful for others, feel free to share it.