Here, to “watch” attentively should not be taken literally to mean seeing with eyes, as eyes cannot see mind. Only mind itself can perceive its own nature. It is said in the texts of Yogacara and Buddhist Logic that mind is self-aware. Non-sentient species or organisms have no sense of self because they don’t have a mind.
~ Depicted from "THE HANDBOOK FOR LIFE"S JOURNEY : On The Three Poisons - How to Confront Anger