The more Spinozistic side of Leibnitz's thought - God as Monad of Monads - is a theistic postulate if hardly a theistic proof.
He starts from the Spinozistic thought that bodily facts and conscious facts, though not reducible one to the other, are different sides of one reality.
Abelard also perceived that Realism, by separating the universal substance from the forms which individualize it, makes the universal indifferent to these forms, and leads directly to the doctrine of the identity of all beings in one universal substance or matter - a pantheism which might take either an Averroistic or a Spinozistic form.
Further, he explained the old Cartesian difficulty of the relation of body and mind by transforming the Spinozistic parallelism of extension and thought into a parallelism between the motions of bodies and the perceptions of their monads; motions always proceeding from motions, and perceptions from perceptions; bodies acting according to efficient causes, and souls according to final causes by appetition, and as if one influenced the other without actually doing so.
The Spinozistic parallelism of extension and thought, and the Leibnitzian parallelism of bodily motion and mental action, incited Schelling and Fechner.