"I shall not, therefore, say any thing further about the nature of mind in general, that secret spring of thought, unknown and unknowable, but shall content myself to observe, in Mr. Locke's method and with his assistance, something about the phænomena of the human mind, by which we may judge surely of the nature, extent, and reality of human knowledge."
— St John, Henry, styled first Viscount Bolingbroke (1678-1751)
(Essay I, §2; vol. iii, pp. 361-2)
See "Letters or Essays Addressed to Alexander Pope, Esq." in the third volume of David Mallet's The Works of the Late Right Honorable Henry St. John, Lord Viscount Bolingbroke, 5 vols. (London : [s.n.], Printed in the Year 1754). <Link to ESTC><Link to ESTC>
Text from the third volume of The Works of the Late Right Honorable Henry St. John, Lord Viscount Bolingbroke, 5 vols. (Dublin: Printed by P. Byrne: 1793). <Link to Google Books>
Reading also in the 1967 reprint of The Works of Lord Bolingbroke, 4 vols. (London: Henry G. Bohn, 1844).