On Life's Value

 Prey aren't even genuinely alive. There's no problem with killing one. Even if there were, they're interchangeable and nothing of value is lost.

 For something genuinely alive, a predator, the value of their life per se is negative. You can say life is [priceless] but only because nobody would buy it. Taking down prey is hard work, and each additional predator is another mouth to feed. Cooperation, or perhaps we can say trust, scales in cost quadratically. The number of relationships in a group scales with the square of the number of members, and (for non-autists) all those relationships require maintenance. Pack hunting is ludicrously effective, but it scales linearly, meaning there's a maximum pack size beyond which each additional pack member cannot possibly pull their own weight. 

 The predator has to pay the pack back for merely existing. Life has negative value. 

 When a new herdbeast is born, it means the grass is grazed faster and the herd needs to move more often. It does pay the herd back by being someone else for the predators to eat, but who cares, it's prey. If there were no predators, prey wouldn't form herds at all. However, if there were no predators, prey would dysgenic'd themselves into extinction. (Ref: Democracy.) During the middle part each herdbeast would be of no value to other herdbeasts (ref: look outside). Without predators, prey masses grow until they have to compete with each other, and they're not equipped with the neurons to handle it. Likewise, because predators do exist, when the herd grows the predator population also grows and the net protection of each new herdbeast is cancelled out. Irrelevant. Prey thinks a larger herd makes them safer, but it doesn't. They're not even alive, and cannot escape insanity or delusion. 

 Prey is only valuable when it loses its life. It is said that death is what gives life meaning - for prey, that's strictly true. By becoming food for a predator, they have value. 

 An immortal is a being who doesn't die even if they don't pay back the debt their existence accrues. A mortal is a being who isn't properly alive and can't conceive of paying back the debts their pseudo-existence accrues.