Baruch Benedict Spinoza developed an enormously elaborate system concerning reality and consequently, it is very challenging to know how to access his work.
He proposed that Ethics is demonstrated in the geometrical manner. Consequently he speaks of things such as axioms and postulates and unfortunately on the whole subsequent philosophers have not taken his arguments very seriously.
Descartes defined substance as a name for that which really exists and which requires nothing but itself in order for it to exist. He further contended that the only true substance is "God". Other things, so to speak, such as the soul or the body are all dependent on God. God is the only absolute substance.
Spinoza took this point and proposed that there is really only one substance, which is the "one thing which is an explanation of itself", whose "nature it is to exist." Spinoza also determined that this one thing whose nature it is to exist should be termed "God" or "Nature."
Spinoza emphasized that God's nature is infinite or has no boundaries. Since God is infinite and has no boundaries, therefore God must be in everything. Thus we have the emergence of Pantheism in Spinoza's thought.
He saw reality as consisting of oneness, but he also acknowledged that there are divisions in that reality. He described these divisions in terms of God's perfection. Nature is the totality of what there is and in that sense God is perfect, but he is identified with a whole array of natural things, which are manifested in diverse manners and forms.
