1. Difference between human and animal

    As from wood, fire can be manifested, or as butter can be churned out of milk, so also the presence of the Lord as Paramatma can be felt by the process of legitimate hearing and chanting of the transcendental subjects which are especially treated in the Vedic literatures like the Upanisads and Vedanta. Srimad-Bhagavatam is the bona fide explanation of these Vedic literatures. The Lord can be realized through the aural reception of the transcendental message, and that is the only way to experience the transcendental subject. As fire is kindled from wood by another fire, the divine consciousness of man can similarly be kindled by another divine grace. His Divine Grace the spiritual master can kindle the spiritual firefrom the woodlike living entity by imparting proper spiritual messages
    injected through the receptive ear. Therefore one is required to approach
    the proper spiritual master with receptive ears only, and thus divine
    existence is gradually realized. The difference between animality and
    humanity lies in this process only. A human being can hear properly, whereas an animal cannot.

    From Srila Prabhupada’s purport to SB 1.2.32