In his book, Understanding Our Own Mind, the Buddhist monk Thich Nhat Hanh tells this story:

If you plant a seed in springtime, by autumn a plant will mature and bear flowers. From those flowers, new seeds will fall to the earth, where they will be stored until they sprout and produce new flowers. Our mind is a field in which every kind of seed is sown—seeds of compassion, joy, and hope, seeds of sorrow, fear, and difficulties.

Every day our thoughts, words, and deeds plant new seeds in the field of our consciousness, and what these seeds generate becomes the substance of our life. There are both wholesome and unwholesome seeds in our mind-field, sown by ourselves and our parents, schooling, ancestors, and society.

If you plant wheat, wheat will grow. If you act in a wholesome way, you will be happy. If you act in an unwholesome way, you will water seeds of craving, anger, and violence in yourself and in others... As we cultivate the seeds of joy and transform seeds of suffering in ourselves, understanding, love, and compassion will flower.