Surveying the "Powers of our own Minds" is like fathoming "the depths of the Ocean": "'Tis of great use to the Sailor to know the length of his Line, though he cannot with it fathom all the depths of the Ocean. 'Tis well he knows, that it is long enough to reach the bottom, at such Places as are necessary to direct his Voyage, and caution him against running upon Shoals, that may ruin him."
— Locke, John (1632-1704)
I find over 25 entries in the ESTC (1690, 1694, 1695, 1700, 1706, 1710, 1715, 1721, 1726, 1731, 1735, 1741, 1748, 1753, 1759, 1760, 1765, 1768, 1775, 1777, 1786, 1788, 1793, 1795, 1796, 1798). See also the many abridgements issued in the period.
First published as An Essay Concerning Humane Understanding. In Four Books. (London: Printed by Eliz. Holt, for Thomas Basset, at the George in Fleetstreet, near St. Dunstan's Church, 1690). <Link to EEBO><EEBO-TCP>
Searching first in a Past Masters edition based on the 12th Edition of Locke's Works and proofread against the 1959 Fraser edition. More recent searches in EEBO-TCP.
Reading John Locke's An Essay Concerning Human Understanding, ed. Peter Nidditch (Oxford, Oxford UP, 1975)--against which I have checked the text searched in Past Masters. Note, Nidditch's text is based on 4th ed. of 1700.