The first precept prohibits the taking of life of a sentient being. It is violated when someone intentionally and successfully kills such a sentient being, having understood it to be sentient and using effort in the process. Causing injury goes against the spirit of the precept, but does, technically speaking, not violate it. The first precept includes taking the lives of animals, even small insects. However, it has also been pointed out that the seriousness of taking life depends on the size, intelligence, benefits done and the spiritual attainments of that living being. Killing a large animal is worse than killing a small animal (also because it costs more effort); killing a spiritually accomplished master is regarded as more severe than the killing of another "more average" human being; and killing a human being is more severe than the killing of an animal. But all killing is condemned. Virtues that accompany this precept are respect for dignity of life, kindness and compassion, the latter expressed as "trembling for the welfare of others". A positive behavior that goes together with this precept is protecting living beings. Positive virtues like sympathy and respect for other living beings in this regard are based on a belief in the cycle of rebirththat all living beings must be born and reborn. The concept of the fundamental Buddha nature of all human beings also underlies the first precept.