Although the New Essays were designed as a response to Locke (who we will read next), its preface is most imformative about Leibniz’s own ideas. Most of the ones he discusses are at least hinted at in the Discourse on Metaphysics, but he gives most of his attention to ideas that received relatively little attention in that work.
After a couple of introductory paragraphs, Leibniz’s preface is divided into extended discussions of each of a small number of broad areas of disagreement with Locke. We will discuss these in two groups of two issues each. The two groups correspond roughly to a division between issues concerning souls and issues concerning matter, and this assignment concerns the former.
• The first topic for today (which, after the introductory paragraphs runs through p. 53) concerns innate ideas. Locke denies that any ideas need be seen as innate and adopts the picture of the mind at birth as a blank tablet. Our interest now is in Leibniz rather than Locke, but you can see the key features of Leibniz’s view of innate ideas by seeing how he tries to respond to Locke. The image of a veined block of marble (on p. 53) is crucial here. Locke grants that the mind has innate abilities, but Leibniz wants something more, innate tendencies.
• The second topic introduces an idea of Leibniz’s that is implicit in the Discourse on Metaphysics but receives its fullest statement in this work. Leibinz said in the Discourse that every substance expressed the whole of the universe, both its history and its future. Here, he describes this expression as a sort of unconscious or only partly conscious perception. The comparison with the sound of water (a waterfall, a mill, the sea) on p. 54 is central here. It appeared in the Discourse in a related context (§33, p. 37), but it is given more emphasis here. Although Leibniz does a number of things with the idea of perceptions that are not conscious (and thus not “apperceptions”), you should notice especially the connection he makes between it and the lack of distinctness in sense impressions. The suggestion is that if such impressions were distinct, we would immediately perceive their physical cause, and that sort of view can be found in Spinoza (who held essentially that souls and bodies were merely different aspects of the same thing). In short, the move from sense impressions to scientific understanding is a matter of making distinct what was initially confused.