 The two key ideas that Wolff takes from Leibniz are, first, the characterization of sensory perception as a clear but confused rather than distinct perception of things that could, at least in principle, be known both clearly and distinctly by the intellect; and, second, the characterization of pleasure as the sensory, and thus clear but confused, perception of the perfection of things. Leibniz’s conception of sensory perception was presented in a 1684 paper entitled “Meditations on Knowledge, Truth, and Ideas.” Here Leibniz stated that “Knowledge is clear…when it makes it possible for me to recognize the thing represented,” but that it is “confused when I cannot enumerate one by one the marks which are sufficient to distinguish the thing from others, even though the thing may in truth have such marks and constituents into which its concept can be resolved.” Conversely, knowledge is both clear and distinct when one can not only clearly distinguish its object from other objects but can also enumerate the “marks” or properties of the object on which that distinction is based.  Leibniz then says that sensory perception is clear but indistinct or confused knowledge, and illustrates his general thesis about sense perception with a remark about the perception and judgment of art: “Likewise we sometimes see painters and other artists correctly judge what has been done well or badly; yet they are often unable to give a reason for their judgment but tell the inquirer that the work which displeases them lacks ‘something, I know not what’” (Leibniz, “Meditations on Knowledge, Truth, and Ideas,” p. 291). This illustration would be decisive for Wolff and all of those whom he in turn influenced.