Good source for animal realm: http://www.tibetanbuddhistaltar.org/the-animal-realm/
From above source:
- "So, in the case of the animals, they themselves are actually helpless. They suffer from being beasts of burden, from our taking their bodies for food; they are harvested like objects, and they have no hope to accomplish Dharma. And this is the suffering of the animal realm."
- "The problem with animals is that they are so instinctual. They are so tightly wrapped in what is a kind of a reactive mode. You would have to say a ‘knee jerk reactive mode.’ Their experience is not the kind of mental deliberation or consideration or even logic that we have, where we can see phenomena, and even with our deluded minds, can sometimes step back from that and say, “Okay, let’s think about what this means.” You see, an animal can’t do that. An animal is going to be deeply and profoundly reactive every time, and they will react only instinctively. So the animal has literally no space in their minds. Everything they feel they react to unthinkingly. That’s why we say animals are dumb. It isn’t because they’re less than us; it is because they’re unthinking. They react only instinctively, which is a kind of core, gross, inconceivably heavy form of emotion, in that emotion comes from instinctual reaction, and is the outgrowth of that. So instinctive reaction is even heavier, even more demanding. You know how you can’t help reacting emotionally. Instinctive reaction is much heavier than that. You can’t even think about hoping to react any other way. It is an automatic and profound knee jerk reaction. So the animals literally cannot practice Dharma."