'In order,' says Leibniz, 'to get a clearer idea of the little perceptions which we cannot distinguish in the crowd, I am accustomed to employ the example of the roar or noise of the sea which strikes us upon the shore. To hear this sound, as we do hear it, we must hear the parts which compose this total, i. e. the sounds of each wave, though each of these little sounds only makes itself perceptible in the confused assemblage of all the others together, (that is to say, in that same roar,) and would not be noticed if this wave which causes it were alone. For we must be a little affected by the movement of that wave, and we must have some perception of each of these sounds, however small they may be; otherwise we should never have the perception of a hundred thousand waves, since a hundred thousand zeros would never make anything.... These little perceptions are of greater efficiency by their consequences than we suppose. It is they which form that _Je ne sais quoi_, those tastes, those images of sensible qualities, clear in the assemblage, but confused in the parts; those impressions made upon us by surrounding bodies which envelop the infinite, that _nexus_ which each being has with all the rest of the universe. It may even be said that in virtue of these little perceptions the present is big with the future and laden with the past, that everything conspires together: and that in the least of substances, eyes as piercing as those of God could read the whole sequel of the things of the universe. 'These insensible perceptions, further, mark and constitute the same individual, who is characterised by the traces or expressions which they preserve of the preceding states of that individual, thus forming the connexion with his present state. These may be known by a superior spirit, though that individual himself should not feel them, i. e. though express memory should no longer be there. But these perceptions also supply the means of rediscovering that memory, at need, by periodic developments, which may one day happen.... It is also by these insensible perceptions that I explain that admirable pre-established harmony of mind and body, and even of all monads or simple substances,--which takes the place of the impossible influence of one upon another.... After this, I should add but little if I said that it is these small perceptions which _determine_ us in many conjunctures without our thinking of it, and which deceive the vulgar by the appearance of an _indifference of equilibrium_, as if we were entirely indifferent whether we turned, e. g., to right or to left.