What is the duty of acharya?

An ācārya is the Supreme Lord’s messenger. He carries the Lord’s message from Vaikuṇṭha and distributes to us. One must hear that message emanating from his mouth through service-inclined ears. If one becomes fully surrendered, by the ācārya’s mercy one will achieve perfection. No one other than an inhabitant of Vaikuṇṭha is able to speak about Vaikuṇṭha. We have to hear about Calcutta from a person who has seen Calcutta. Then only will we get a true message.