From the Assu Sutta (SN 15.3) in the Pali Canon (trans. Thanissaro Bhikkhu):
There the Blessed One said: “From an inconstruable beginning comes transmigration. A beginning point is not evident, though beings hindered by ignorance and fettered by craving are transmigrating & wandering on. What do you think, monks: Which is greater, the tears you have shed while transmigrating & wandering this long, long time — crying & weeping from being joined with what is displeasing, being separated from what is pleasing — or the water in the four great oceans?”
“As we understand the Dhamma taught to us by the Blessed One, this is the greater: the tears we have shed while transmigrating & wandering this long, long time — crying & weeping from being joined with what is displeasing, being separated from what is pleasing — not the water in the four great oceans.”
“Excellent, monks. Excellent. It is excellent that you thus understand the Dhamma taught by me.
Or from the Lotus Sutra, chapter 3 (Gene Reeves translation):
“He [The Buddha] sees how living beings are scorched by the fires of birth, old age, disease and death, anxiety, sorrow, suffering, and agony. Moreover, because of the five desires and the desire for wealth, they undergo all kinds of suffering. Because of attachment to desire and striving, they endure much suffering in this life and later will suffer in a purgatory, or as animals or hungry spirits. Even if they are born in a heaven, or among people, they will experience many kinds of suffering, such as the suffering of poverty and hardship, the suffering of separation from what they cherish, or the suffering from encountering what they hate.
“Absorbed in these things, living beings rejoice and amuse themselves, without knowing or seeing or being alarmed or frightened. And never being dissatisfied, they never try to liberate themselves. In the burning house of this threefold world they run about here and there, and, though they encounter great suffering, they are not disturbed by it.”
Something I felt like posting tonight.