If sensation is to be the mother of thought, and the latter at the same time to preserve its character as original, i.e., as something not obtained from without, sensation must, first, include an unconscious thinking in itself, and, secondly, must itself receive a title to originality and spontaneity.  As the Catholic dogma added the immaculate conception of the mother to that of the Son, so Leibnitz transfers the (virginal) origin of rational concepts, independent of external influence, to sensations.  The monad has no windows.  It bears germinally in itself all that it is to experience, and nothing is impressed on it from without.  The intellect should not be compared to a blank tablet, but to a block of marble in whose veins the outlines of the statue are prefigured.  Ideas can only arise from ideas, never from external impressions or movements of corporeal parts.  Thus all ideas are innate in the sense that they grow from inner germs; we possess them from the beginning, not developed (explicite), but potentially, that is, we have the capacity to produce them.  The old Scholastic principle that “there is nothing in the understanding which was not previously in sense” is entirely correct, only one must add, except the understanding itself, that is, the faculty of developing our knowledge out of ourselves.  Thought lies already dormant in perception.  With the mechanical position (sensuous representation precedes and conditions rational thought) is joined the teleological position (sensuous representations exist, in order to render the origin of thoughts possible), and with this purposive determination, sensation attains a higher dignity:  it is more than has been seen in it before, for it includes in itself the future concept of the understanding in an unconscious form, nay, it is itself an imperfect thought, a thought in process of becoming.  Sensation and thought are not different in kind, and if the former is called a passive state, still passivity is nothing other than diminished activity.  Both are spontaneous; thought is merely spontaneous in a higher degree.

[Footnote 1:  A careful comparison of Locke’s theory of knowledge with that of Leibnitz is given by G. Hartenstein, Abhandlungen der k. saechs.  Gesellschaft der Wissenschaften, Leipsic, 1865, included in Hartenstein’s Historisch-philosophische Abhandlungen, 1870.]

By making sensation and feeling the preliminary step to thought, Leibnitz became the founder of that intellectualism which, in the system of Hegel, extended itself far beyond the psychological into the cosmical field, and endeavored to conceive not only all psychical phenomena but all reality whatsoever as a development of the Idea toward itself.  This conception, which may be characterized as intellectualistic in its content, presents itself on its formal side as a quantitative way of looking at the world, which sacrifices all qualitative antitheses in order to arrange the totality