He basically said that there was a human soul, but that it wasn't made up of things that couldn't be measured. He thought that the soul was just as profound, or even more profound, if it obeyed laws of physics. My amusement was that a thread on something like the altering of mental state due to artificially introducing lithium into ones diet is amusing, since a philosopher that was very concerned with the philosophy of mind and soul (Spinoza) would have been fascinated by this type of intentional soul alteration.