If you are ever going to get more than a brief understanding of pantheism then it is vital to get to grips with understanding Spinoza. Spinoza was not the first pantheist, but he is probably the most influential pantheist since the time of the enlightenment. The decline of theism and the rise of alternative beliefs can be traced back directly and indirectly to Spinoza. He was not only a chief architect in the rise and success of science; he was also a fundamental force behind the gradual decline of theological authority. Understanding Spinoza is not easy, but the difficulties involved in grasping his ideas are no less worthy of making the effort.
If you were to take a random page and quote form Spinoza’s main work, the ethics, you will no doubt find a sentence in which you understand all of the individual words. Yet I am reasonably sure that you would also find a sentence which is seemingly incomprehensible too. For example: The first axiom that Spinoza presents is “Everything which exists, exists either in itself or in something else.”
An axiom is something that is assumed to be self evidently true, so Spinoza must have presented this axiom as something which he believed to be one of nature’s ultimate and self evident truths. The whole of Spinoza’s philosophy is set out in this way. He begins with a set of definitions, which he then uses to write his axioms. He then moves to working out how the universe must be given his definitions and on the assumption that his axioms are in fact true. To that extent his work is a work in logic, similar to a Euclidean system. It is probably the case that if you were to agree and accept just one of his axioms then you are logically committed to accepting his other axioms which follow rationally and necessarily from each other. In doing this Spinoza creates a set of principles and consequently a metaphysical system which he considers to be how the universe must be.