Some people think that causes are not necessary. They think that things do not need causes and can exist without them. This is mistaken. Think about it. If you plant a seed in a flowerpot, a flower will grow. It will not grow from this table in front of me now. What is the reason for that? The causes for a flower are present in a flowerpot, and for that reason, a flower can grow there. The causes for a flower are not present on the surface of this table, and for that reason, a flower cannot grow there. If things arose in the absence of causes, a flower would have to be able to grow from the surface of this table even though the causes for a flower are not present there. Or, as we know, flowers bloom in the summer but not in the winter. What is the reason for that? In the summer, the causes and conditions for the growth of flowers are complete. In the winter, they are not. In dependence upon that, flowers grow in the summer but not in the winter. If causes were not necessary, flowers would grow in the winter also. They would grow at all times.

-- Thrangu Rinpoche