For if we each selfishly pursue only what we believe to be in our own interest, without caring about the needs of others, we not only may end up harming others but also ourselves. This fact has become very clear during the course of this century.
 14th Dalai Lama, Nobel Lecture (1989). copy citation

Context

“The realisation that we are all basically the same human beings, who seek happiness and try to avoid suffering, is very helpful in developing a sense of brotherhood and sisterhood; a warm feeling of love and compassion for others. This, in turn, is essential if we are to survive in this ever shrinking world we live in. For if we each selfishly pursue only what we believe to be in our own interest, without caring about the needs of others, we not only may end up harming others but also ourselves. This fact has become very clear during the course of this century. We know that to wage a nuclear war today, for example, would be a form of suicide; or that by polluting the air or the oceans, in order to achieve some short-term benefit, we are destroying the very basis for our survival.” source