In Kṛṣṇa consciousness we address our contemporaries as "prabhu." Prabhu means master. And the real idea is that "You are my master, I am your servant." Just the opposite number. Here, in the material world, everyone wants to place himself as the master. "I am your master, you are my servant." That is the mentality of material existence. And the spiritual existence means "I am the servant, you are the master." Just see. Just the opposite number.
Bhagavad-gītā 4.9 -- Montreal, June 19, 1968