The Four Thoughts
These are the four contemplations that turn the mind away from samsara.
The first two reflections are:
(1) The difficulty of finding the freedoms and advantages
(2) The impermanence of life
These two contemplations turn the mind away from the concerns of this life.
The second two reflections are:
(3) Karma (action, cause and effect)
(4) The defects of samsara
These two contemplations turn the mind away from our limited attitudes and conduct with respect to future lives.
The Four Thoughts from Buddhist Teachings
This free and well-favoured human form is difficult to obtain.
Now that you have the chance to realize the full human potential,
If you don’t make good use of this opportunity,
How could you possibly expect to have such a chance again?
—from the Bodhicharyavatara.
This existence of ours is as transient as autumn clouds.
To watch the birth and death of beings is like looking at the movement of a dance.
A lifetime is like a flash of lightning in the sky,
Rushing by, like a torrent down a steep mountain.
—from the Lalitavistara Sutra
When his time has come, even a king has to die,
And neither his friends nor his wealth can follow him.
So for us—wherever we stay, wherever we go—
Karma follows us like a shadow.
—from the Rajavavadaka Sutra
Because of craving, attachment and ignorance,
Men, gods, animals, hungry ghosts and hell-beings
Foolishly go round,
Like the turning of a potter’s wheel.
—from the Lalitavistara Sutra
Source: Based on https://www.rigpawiki.org/index.php?title=Four_thoughts