diff --git a/004/codex-004.tex b/004/codex-004.tex
index c5b66a8..751169c 100644
--- a/004/codex-004.tex
+++ b/004/codex-004.tex
@@ -320,27 +320,34 @@ Even better, NAPS2 had an ``interleave'' feature, which meant that I didn't need
 
 The only problem was that NAPS2 offered \textit{four} versions of this command: interleave, deinterleave, alternate interleave, and alternate deinterleave. (These are very neatly contained under the ``Reorder'' icon in the main menu.) I knew one of those was what I needed; I just needed to figure out which.
 
+I'm a scientist, so I experimented. I took five sheets of paper, wrote the odd numbers 1-9 on the front side and the corresponding even numbers 2-10 on the back side. If you flipped through them, you would see something like what you see in figure \ref{naps2-orig}
 
 \begin{figure}[h]
 \caption{The document as originally drawn}
+\label{naps2-orig}
 \centering
 \kpage{1}\kpage{2}\kpage{3}\kpage{4}\kpage{5}\kpage{6}\kpage{7}\kpage{8}\kpage{9}\kpage{10}
 \end{figure}
 
+Because I wrote on both sides of each side of paper (in order to emulate a double-sided original), I scanned the pages, and then flipped them over and scanned the other sides. And because I am scanning these upside down, the even numbers end up in reverse order. So I ended up with a pdf that looked like figure \ref{naps2-scan}.
 
 \begin{figure}[h]
 \caption{The document as originally scanned}
+\label{naps2-scan}
 \centering
 \kpage{1}\kpage{3}\kpage{5}\kpage{7}\kpage{9}\kpage{10}\kpage{8}\kpage{6}\kpage{4}\kpage{2}
 \end{figure}
 
+That's progress, but it's not the progress I wanted to make. I tried all the different options available under the ``Reorder'' icon, and finally figured out that ``Alternate Interleave'' would produce the final pdf that I want, which you can see in figure \ref{naps2-final}.
 
 \begin{figure}[h]
 \caption{The document after applying ``Alternate Interleave''}
+\label{naps2-final}
 \centering
 \kpage{1}\kpage{2}\kpage{3}\kpage{4}\kpage{5}\kpage{6}\kpage{7}\kpage{8}\kpage{9}\kpage{10}
 \end{figure}
 
+If that looks like the original document, it is definitely not an accident; it is by design. Print that out and you get something close to the original.\footnote{I say ``close'' because a scan is never the equivalent of the original. It is a reflection, an imitation. But it is not the same. Every time we copy an analog object, we lose something. Replicative failure is a thing.}
 
 \chapter{Chemistry in \LaTeX{}}