"Is that how it came to be? Why would it have? IF we are all just evolved from pond scum, how in the world did our brain "build and engineer" this eyeball? Did our brains theorize "if I just combine these cells together to form a lens that is curved this certain way, it will be able to focus light"?? I mean think about that!" smile
Richard, back in 1980 I decided I wanted to read and truly understand Darwin's "The Origin Of Species". I think it took me at least two months to finish it; I read it very slowly and went over each paragraph more than once, if necessary, to make sure I understood what was being written. It's one of those books, similar to Dostoyevsky's novels, that you have to really want to read to get through it.
I clearly remember after finishing it that I considered myself to have acquired a profound sense of understanding the workings of nature. The natural world actually looked different to me.
When I hear any criticism of Darwin, I'm inclined to ask myself if that individual has actually read and understood the book. I'm inclined to think probably not.
Anyway, I think if you will take the time to read the book, some of your questions may be answered.
Of course, Sagan couldn't answer where the "pond scum" came from, although I'm inclined to think that now he likely knows all that is presently unknown to man.