"Surely You're Joking, Mr. Feynman!" - unam.

have a better idea of what 'essential object' means. Is a brick an essential object?"
What I had intended to do was to find out whether they thought theoretical
constructs were essential objects. The electron is a theory that we use; it is so useful in
understanding the way nature works that we can almost call it real. I wanted to make the
idea of a theory clear by analogy. In the case of the brick, my next question was going to
be, "What about the inside of the brick?" ­­ and I would then point out that no one has
ever seen the inside of a brick. Every time you break the brick, you only see the surface.
That the brick has an inside is a simple theory which helps us understand things better.
The theory of electrons is analogous. So I began by asking, "Is a brick an essential
object?"
Then the answers came out. One man stood up and said, "A brick as an
individual, specific brick. That is what Whitehead means by an essential object."
Another man said, "No, it isn't the individual brick that is an essential object; it's
the general character that all bricks have in common ­­ their 'brickness' ­­ that is the
essential object."
Another guy got up and said, "No, it's not in the bricks themselves. 'Essential
object' means the idea in the mind that you get when you think of bricks."
Another guy got up, and another, and I tell you I have never heard such ingenious
different ways of looking at a brick before. And, just like it should in all stories about
philosophers, it ended up in complete chaos. In all their previous discussions they hadn't
even asked themselves whether such a simple object as a brick, much less an electron, is
an "essential object."
After that I went around to the biology table at dinner time. I had always had
some interest in biology, and the guys talked about very interesting things. Some of them
invited me to come to a course they were going to have in cell physiology. I knew
something about biology, but this was a graduate course. "Do you think I can handle it?
Will the professor let me in?" I asked.
They asked the instructor, E. Newton Harvey, who had done a lot of research on
light­producing bacteria. Harvey said I could join this special, advanced course provided
one thing ­­ that I would do all the work, and report on papers just like everybody else.
Before the first class meeting, the guys who had invited me to take the course
wanted to show me some things under the microscope. They had some plant cells in
there, and you could see some little green spots called chloroplasts (they make sugar
when light shines on them) circulating around. I looked at them and then looked up:
"How do they circulate? What pushes them around?" I asked.
Nobody knew. It turned out that it was not understood at that time. So right away
I found out something about biology: it was very easy to find a question that was very
interesting, and that nobody knew the answer to. In physics you had to go a little deeper
before you could find an interesting question that people didn't know.
When the course began, Harvey started out by drawing a great, big picture of a
cell on the blackboard and labeling all the things that are in a cell. He then talked about
them, and I understood most of what he said.
After the lecture, the guy who had invited me said, "Well, how did you like it?"
"Just fine," I said. "The only part I didn't understand was the part about lecithin.
What is lecithin?"
The guy begins to explain in a monotonous voice: "All living creatures, both plant