Although the very name "spiritual master" self-explanatory, sometimes a question arises for both newcomers and veteran devotees; is the spiritual master present beyond the physical? Can his teachings be understood even after his departure from this world? And can he still be accepted as a worshipful spiritual master? Srila Prabhupada clears up all these questions in the following excerpt from Krsna; The Reservoir of Pleasure.
Some people argue that Arjuna was talking with Krsna because Krsna was present before him, whereas in my case, Krsna is not present. So how can I get directions? But that is not a fact. Krsna is present by His words—the Bhagavad-gita. In India, when we speak on the Bhagavad-gita or Srimad-Bhagavatam, we regularly perform worship with flowers, or with other paraphernalia, as is required for worshiping. In the Sikh religion also, although they have no form of the Deity, they worship the book Granthasahib. Perhaps some of you are acquainted with this Sikh community. They worship this Grantha. Similarly, the Moslems worship the Koran. Similarly, in the Christian world, the Bible is worshiped. It is a fact that the Lord Jesus Christ is present by His words. Krsna is also present by His words.
These personalities, either God or the son of God, who come from the transcendental world, keep their transcendental identities without being contaminated by the material world. That is their omnipotence. We are in the habit of saying that God is omnipotent. Omnipotence means that He is not different from His name, from His quality, from His pastimes, from His instruction. Therefore, the discussion of Bhagavad-gita is as good as discussion with Krsna Himself.