The principle has a variety of expressions, all of which are
perhaps best summarized by the following: A sufficient
explanation may be understood either in terms of reasons or
causes for like many philosophers of the period, Leibniz did not
carefully distinguish between the two. The resulting principle
is very different, however, depending on which interpretation is
given. In fact Leibniz opposed fatalism and had a more nuanced
and characteristic version of the principle, in which the
contingent was admitted on the basis of infinitary reasons, to
which God had access but humans did not. He explained this while
discussing the problem of the future contingents: We have said
that the concept of an individual substance [Leibniz also uses
the term haecceity ] includes once for all everything which can
ever happen to it and that in considering this concept one will
be able to see everything which can truly be said concerning the
individual, just as we are able to see in the nature of a circle
all the properties whi