"To think often, and never retain it so much as one moment, is a very useless sort of thinking: and the Soul in such a state of thinking, does very little, if at all, excel that of a Looking-glass, which constantly receives variety of Images, or Ideas, but retains none; they disappear and vanish, and there remain no footsteps of them; the Looking-glass is never the better for such Ideas, nor the Soul for such Thoughts."
— 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.