In our own case it is most likely that it is only this one time that we will be born as a human with the precious qualities. However this is not the case. Life is fleeting, highly perishable, and passes in a flash, like lightning in the night sky. Human life is difficult to find because it is a result that arises from certain causes and it is rare for beings to create these causes. One can see that human life is difficult to find when one considers the enormous numbers of sentient beings and realizes that humans are only a tiny fraction of that number.
Human life arises from certain causes and conditions.
Of particular importance is to live a pure, ethical life. This is the main cause of gaining a human life in the future. Even by following the lay ethics such a life can be gained. These are the teachings about precious human rebirth and the qualities of human life that Buddha taught and that are recorded in the scriptures. Things which seemed like contradictions at first are clarified, and an ever-increasing understanding arises.