Let me define “Darshan” for you. Broadly, from a lower perspective, Darsana (Sanscrit) means “sight” of a gross or subtle object of reverence in the form of an idol or an image, or perhaps even a place or a building. Paying homage, bowing, prostrations and salutations (verbal) are generally the gestures common to Darsana. You are humbled before a higher force. So, the only truth of Darsana is the seer. The intensity of Maya!
From a higher perspective, let the higher force push you inside yourself: your mind is coerced and conditioned. Because you are coerced into thinking by elders that you are separated from the divine you run here and thither seeking (to absolve your sins perhaps)? Being born is the greatest sin. True Darsana is being, is your own true nature. When are you ever in the absence of Darsana? Find out who is the “seer.” Are you not in full Darshana in deep sleep? At the age of eleven, in a toilet of a Gurudwara, Dippack insightfully realized “God is everywhere”! Darsana is everywhere and the core of your being, your life (being-consciousness) is Darsana! True Darsana is beyond the seer, the here and the now!
Let me define “Satsang” for you. Broadly. From a lower perspective, Sat-Sang means in the association/company (sang) of the essence of truth (sat); thus arises the need for spiritual gathering or discourse, or Upanishad (sitting or association next to Guru: disciple sitting down near his teacher at the time of discourse), or sacred gathering. Only if the “I am the body-sense” or the “I-thought” or “I am this body and form” arises, does the sense of aspiring to come into close proximity or contact with the essence of truth arises.
From a higher perspective, let me push you inside yourself: You have forgotten your true nature, like seeking to find your sunglasses adorned on your forehead you ask a Guru to tell you where your sunglasses lay hidden. Satsang means separation or duality or viyoga. Are you ever separated from That? Who separates you from That? Thoughts! True Satsang is in deep sleep, because there is only That in deep sleep and That You Are! So close or the closest contact you will ever have—Your own Existence! That is your true nature. Your Life (Being-Consciousness) is the Holy Grail of Bliss and the True Satsang!
So, you may well ask what is the difference between Darsana and Satsang. From a higher perspective, non whatsoever. Darsana and Satsang are one and the same thing, viz., you cannot have one and and not the other from a higher perspective, for they are not apart. Simultaneous illumination of Satsang and Darshan is the Self or Atma-Nishta; it is within the Self and the Self. There is nothing besides the Self nor apart from the Self. Show me the difference. But from the view of the lower perspective, they appear or are semingly different due to the intensity of Maya.
