Charles Darwin's studies at the University of Cambridge included two other texts by Paley, and in his final exams in January 1831 he did well in questions on these texts.
He had to stay on until June, and read Paley's Natural Theology as well as John Herschel's Preliminary Discourse on the Study of Natural Philosophy and Alexander von Humboldt's Personal Narrative: these books inspired "a burning zeal" to research natural history.
After the Beagle voyage he began development of his theory of natural selection, and in 1838 opened a notebook listing "books to be read", including "Paley's Nat.
Theology".
In 1859, on completing On the Origin of Species, he told a friend "I do not think I hardly ever admired a book more than Paley's Natural Theology: I could almost formerly have said it by heart."

He later stated in his autobiography that he was initially convinced by the argument:
Although I did not think much about the existence of a personal God until a considerably later period of my life, I will here give the vague conclusions to which I have been driven.
The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered.
We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man.
There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows.
Everything in nature is the result of fixed laws.

— Charles Darwin, The Autobiography of Charles Darwin
Charles Darwin's studies at the University of Cambridge included two other texts by Paley, and in his final exams in January 1831 he did well in questions on these texts. He had to stay on until June, and read Paley's Natural Theology as well as John Herschel's Preliminary Discourse on the Study of Natural Philosophy and Alexander von Humboldt's Personal Narrative: these books inspired "a burning zeal" to research natural history. After the Beagle voyage he began development of his theory of natural selection, and in 1838 opened a notebook listing "books to be read", including "Paley's Nat. Theology". In 1859, on completing On the Origin of Species, he told a friend "I do not think I hardly ever admired a book more than Paley's Natural Theology: I could almost formerly have said it by heart."
He later stated in his autobiography that he was initially convinced by the argument:
Although I did not think much about the existence of a personal God until a considerably later period of my life, I will here give the vague conclusions to which I have been driven. The old argument of design in nature, as given by Paley, which formerly seemed to me so conclusive, fails, now that the law of natural selection has been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows. Everything in nature is the result of fixed laws.
— Charles Darwin, The Autobiography of Charles Darwin
Natural Theology or Evidences of the Existence and Attributes of the Deity