That Spinoza had a keen interest in science and that he strove to examine and understand external bodies and the human body, as far as possible using the science of his day, seems clear from reading some of his letters and also parts of his philosophy. Some people seem to think that modern science has advanced so far from Spinoza's day that his philosophy is obsolete. Others may think, because his conclusions from physical experiments are seen to be flawed, that his philosophy is flawed too --as though he based his philosophy on abstract science and the results of physical experimentation. If we look carefully at his philosophic writings it should be clear that Spinoza never claimed to have attained or to be able to attain an adequate idea of any bodies by way of the abstractions of number, measure, time, etc. or by performing physical experiments.

    In his letter to Oldenburg regarding Boyle's book on Nitre, Fluidity, and Solidity Spinoza makes some comments about Boyle's experiments and the conclusions he has drawn there and then says; "I shall set out briefly what occurs to me as the simplest explanation of this Phenomena ..." and describes his observations from further experiments and offers comments in support of his imagination about what is happening. He describes various forms of particles with hollow passages, etc. which change under application of heat or in the presence of other particles. He had not seen any such particles and did not know if this was actually so. Rather he was using his imagination and some simple ideas about bodies in trying to explain the phenomena observed in the experiments. He says nothing about having any clear ideas of what is actually happening.

    This seems to me similar to what happened when the automobile became popular and those of a mechanical mind began to experiment and discovered the effects of such things as advancing or retarding the timing of the spark in the cylinders or the opening and closing of the valves depending on the speed and load on the engine and observing the resulting phenomena. These were experiments. They had some general idea of what was going on but, as they observed the changes in power under particular conditions, they did not actually know why these changes occurred but still they began to form ideas about the burning speed of the fuel, etc. So Spinoza experimented with chemistry, he also ground precision lenses but his philosophy is not based on the knowledge of optics he gained in so doing.

    More recent physical experimentation, measurement, and theory has not changed anything about Spinoza's Philosophy other than perhaps to make his reference regarding the sun; that it is "distant from us more than six hundred of the earth's diameters" seem quaint and his description of a possible mechanism for memory perhaps even sound absurd. BUT, after discoursing on bodies in the Ethics and describing this possible mechanism for memory he says; "It is possible that the same result may be brought about by other causes; but I think it suffices for me here to have indicated one possible explanation, just as well as if I had pointed out the true cause." This is the same kind of thing he was doing with the Nitre experiments. Whether he believed that he was close to the truth or not is inconsequential --He knew, and he did not claim otherwise, that he did not have an adequate idea of the distance to the sun, the actual mechanism for memory, or the actual nature of Niter. In his Ethics he says:

========= E2: PROP. 16, Corollary 2:
...the ideas, which we have of external bodies, indicate rather the constitution of our own body than the nature of external bodies.
=========

and, working through several subsequent propositions which I hope we will one day get through in this slowww reading list, he then says:

========= E2: PROP. 29, Corollary:
--Hence it follows that the human mind, when it perceives things after the common order of nature, has not an adequate but only a confused and fragmentary knowledge of itself, of its own body, and of external bodies.
=========

    So can the human mind have any adequate ideas? Further along he says:

========= E2: PROP. 38:
Those things, which are common to all, and which are equally in a part and in the whole [and which do not constitute the essence of any particular thing], cannot be conceived except adequately.
=========

...and shortly we come to the proposition which is mentioned in the recent posts:

========= E2: PROP 40:
Whatsoever ideas in the mind follow from ideas which are therein adequate, are also themselves adequate.
=========

    The note to this proposition, as we've seen, points out that the Second Kind of Knowledge is based on these "things, which are common to all" and he will also point toward particular adequate ideas, involved in the Third Kind of Knowledge, but we will have to work through to Part 5 to see that:

========= E5: PROP. 30:
Our mind, in so far as it knows itself and the body under the form of eternity, has to that extent necessarily a knowledge of God, and knows that it is in God, and is conceived through God.
=========

    If we do study through the Ethics it becomes clear that when he says; "...knows itself and the body under the form of eternity" he does not mean having physical or chemical evidence of how flesh and blood works but rather he is referring to knowing it most intimately and directly "from the inside" so to speak!

    Of course, simply quoting these propositions here without the proofs and without having worked our way through step-by-step from beginning to end (as Spinoza's asks us to do) will probably not help those who either have not read the Ethics at all or who are just looking for someone to give them a summary in 50 words or less.

    Spinoza makes no claim to having adequate ideas of the actual nature of the Moon or any other external bodies, including bananas in a tree, other than as explained in the Ethics. I would hope that all readers of these messages would at least have some feeling they are going to have to study through the Ethics from beginning to end, step-by-step, before they can even hope to begin to know and understand the ideas expressed there.