knowledge, a further distinction is made between primary truths (which
need no proof) and derived truths. The highest truths of reason are the
identical principles, which are self-evident; from these intuitive truths
all others are to be derived by demonstration--proof is analysis and, as
free from contradictions, demonstration. The primitive truths of experience
are the immediate facts of consciousness; whatever is inferred from them is
less certain than demonstrative knowledge. Nevertheless experience is not
to be estimated at a low value; it is through it alone that we can assure
ourselves of the reality of the objects of thought, while necessary truths
guarantee only that a predicate must be ascribed to a subject (_e.g._, a
circle), but make no deliverance as to whether this subject exists or not.]

To the broad and comprehensive tendency which is characteristic of
Leibnitz's thinking, philosophy owes a further series of general laws,
which all stand in the closest relation to one another and to his
monadological and harmonistic principles, viz., the law of continuity, the
law of analogy, the law of the universal dissimilarity of things or of the
identity of indiscernibles, and, finally, the law of the conservation of
force.

The most fundamental of these laws is the _lex continui_. On the one hand,
it forbids every leap, on the other, all repetition in the series of beings
and the series of events. Member must follow member without a break and
without superfluous duplication; in the scale of creatures, as in the
course of events, absolute continuity is the rule. Just as in the monad one
state continually develops from another, the present one giving birth
to the future, as it has itself grown out of the past, just as nothing
persists, as nothing makes its entrance suddenly or without the way being
prepared for it, and as all extremes are bound together by connecting
links and gradual transitions,--so the monad itself stands in a continuous
gradation of beings, each of which is related to and different from each.
Since the beings and events form a single uninterrupted series, there are
no distinctions of kind in the world, but only distinctions in degree. Rest
and motion are not opposites, for rest may be considered as infinitely
minute motion; the ellipse and the parabola are not qualitatively
different, for the laws which hold for the one may be applied to the other.
Likeness is vanishing unlikeness, passivity arre