"They know, that a human body is a mighty complicated machine: That many secret powers lurk in it, which are altogether beyond our comprehension: That to us it must often appear very uncertain in its operations: And that therefore the irregular events, which outwardly discover themselves, can be no proof, that the laws of nature are not observed with the greatest regularity in its internal operations and government."
— Hume, David (1711-1776)
First published as Philosophical Essays Concerning Human Understanding (London: Printed for A Millar, 1748). <Link to ECCO><Link to ECCO-TCP><Link to 1748 edition in Google Books> "Second edition" in 1750, "third edition" in 1756. First titled An Enquiry Concerning Human Understanding in 1758.
In ECCO-TCP, see also Essays and Treatises: on Several Subjects. By David Hume, Esq, 4 vols. (London: Printed for A. Millar; and A. Kincaid and A. Donaldson, at Edinburgh, 1760). <Link to vol. III>
Text from David Hume, Enquiries Concerning Human Understanding and Concerning the Principles of Morals. 3rd edition. Ed. L. A. Selby-Bigge; P. H. Nidditch (Oxford: Oxford University Press, 1975). Note, Nidditch reproduces the the second volume of the posthumous edition of 1777, which he has collated with the preceding 1772 edition.