on and separation of parts, they
cannot come into being or pass out of it in any natural way whatever, but
only by creation or annihilation. Their non-spatial or punctual character
implies the impossibility of all external influence, the monad develops its
states from its own inner nature, has need of no other thing, is sufficient
unto itself, and therefore deserves the Aristotelian name, entelechy.

Thus two lines of thought combine in the concept of the monad. Gratefully
recognizing the suggestions from both sides, Leibnitz called Cartesianism
the antechamber of the true philosophy, and atomism the preparation for
the theory of monads. From the first it followed that the substances were
self-acting forces; from the second, that they were immaterial units.
Through the combination of both determinations we gain information
concerning the kind of force or activity which constitutes the being of the
monad: the monads are representative forces. There is nothing truly real in
the world save the monads and their representations [ideas, perceptions].

In discussing the representation in which the being and activity of the
monads consist, we must not think directly of the conscious activity of
the human soul. Representation has in Leibnitz a wider meaning than that
usually associated with the word. The distinction, which has become of the
first importance for psychology, between mere representation and conscious
representation, or between perception and apperception, may be best
explained by the example of the sound of the waves. The roar which we
perceive in the vicinity of the sea-beach is composed of the numerous
sounds of the single waves. Each single sound is of itself too small to be
heard; nevertheless it must make an impression on us, if only a small one,
since otherwise their total--as a sum of mere nothings--could not be
heard. The sensation which the motion of the single wave causes is a weak,
confused, unconscious, infinitesimal perception (_petite, insensible
perception_), which must be combined with many similar minute sensations
in order to become strong and distinct, or to rise above the threshold of
consciousness. The sound of the single wave is felt, but not distinguished,
is perceived, but not apperceived. These obscure states of unconscious
representation, which are present in the mind of man along with states of
clear consciousness, make up, in the lowest grade of existence, the whole
life of the monad. The