Prabhupāda: One who is to be followed, that is called ācārya. So who is following the ācārya? Nobody is following. Ācārya is there, but nobody is following ācārya. Ācaraṇa. Ācaraṇa means behavior. Ācārya, that "This man is ideal. One should follow him." That is called ācārya.
(Srila Prabhupada Morning Walk, Los Angeles, December 20, 1973)