Robert A. Duff about Spinoza

The main principle to which Spinoza unswervingly holds is that Nature is a
systematic whole, concatenated in all its parts. Nature, however, is not for
him the physical world, but the whole of Reality. Being the whole of
Reality, we cannot speak of it as the 'other' or the limit of God, but as
the Nature of God, or what God is. Of Nature in this sense, i.e. as
including all existence, the conscious and self-conscious, as well as the
mechanical and the organic, man is and must be a part. His relation to this
system is intrinsic, essential, permanent. Whatever qualities, endowments,
attributes, he may have, cannot be in conflict with this necessary
dependence. If he can exercise reason, will, moral choice, these must be
consistent with the unity in which he stands with all the rest of Nature,
and be subject to its universal laws.

(For more see http://www.euronet.nl/~advaya/spinoza.htm#04)