"It would be nonsense to say that it was not in the interests of a stone to be kicked along the road...A stone has no interests because it cannot suffer. The capacity for suffering and enjoyment is, however, not only necessary, but also sufficient for us to say that a being has interests - at an absolute minimum, an interest in not suffering. A mouse, for example, does have an interest in not being kicked along the road because it will suffer if it is."