The Buddha-Carita or The Life of Buddha by Ven. Aśvaghoṣa

Buddha-carita, or The Life of Buddha - 181
43. Alas, inexorably this is in an especial degree the law of action (karma) in the
world; this is the nature of the world and yet they do not see it to be such.
44. Others, who have disjoined themselves from sensual passion, conclude in their
minds that their station is eternal (dhruva); yet they fall miserably from heaven.
45. In the hells (apāya) is excessive torture, among animals eating each other, the
suffering of hunger and thirst among the pretas, among men the sufferings of
longings,
46. In the heavens that are free from love the suffering of rebirth is excessive. For the
ever-wandering world of the living there is most certainly no peace anywhere.
47. This stream of the cycle of existence has no support and is ever subject to death.
Creatures, thus beset of all sides, find no resting place.
48. Thus with the divine eyesight (divyacakṣus) he examined the five spheres of life
and found nothing substantial in existence, just as no heartwood is found in a
plaintain-tree when it is cut open.
49. Then as the third watch of that night drew on, the best of those who understood
trance (dhyāna) meditated on the real nature of this world:—
50. “Alas! Living creatures obtain but toil; over and over again they are born, grow
old, die, pass on and are reborn.
51. Further man’s sight is veiled by passion (rāga) and by the darkness of delusion
(moha), and from the excess of his blindness he does not know the way out of this
great suffering.”
52. After thus considering, he reflected in his mind, “What is it verily, whose existence
causes the the approach of old age (jarā) and death (maraṇa)?”
53. Penetrating the truth to its core, he understood that old age and death are
produced, when there is birth (jāti).
54. He saw that head-ache is only possible when the head is already in existence; for
when the birth of a tree has come to pass, then only can the felling of it take place.
55. Then the thought again arose in him, “What does this birth proceed from?” Then
he saw rightly that birth is produced from existence due to the power of the act
(karmabhava).
56. With his divine eyesight he saw that active being (pravtti) proceeds from the act,
not from a Creator (Iśvara) or from Nature (Prakti?) or from a self without a cause.
57. Just as, if the first knot in a bamboo is wisely cut, everything quickly comes into
order, so his knowledge advanced in proper order.