These basic tenants are found in the Four Noble Truths and the Eight-fold Path. Let us begin with the Four Noble Truths. The First Noble Truth is that there is pain and suffering in the world. Gautama realized that pain and suffering are omnipresent in all of nature and human life. To exist means we will all encounter suffering.
Birth is painful and so is death.
Sickness and old age are painful. Throughout life, all living things encounter suffering. The Second Noble Truth relates to the cause of suffering. Gautama believed the root cause of suffering is desire. It is the craving for wealth, happiness, and other forms of selfish enjoyment which cause suffering.