ifficult things to
acquire; and after they are acquired it is difficult to keep them in
the head. But they are very valuable. They are like the cattle-pens of a
ranch--they shut in the several brands of historical cattle, each within
its own fence, and keep them from getting mixed together. Dates are hard
to remember because they consist of figures; figures are monotonously
unstriking in appearance, and they don't take hold, they form no
pictures, and so they give the eye no chance to help. Pictures are the
thing. Pictures can make dates stick. They can make nearly anything
stick--particularly IF YOU MAKE THE PICTURES YOURSELF. Indeed, that
is the great point--make the pictures YOURSELF. I know about this from
experience. Thirty years ago I was delivering a memorized lecture every
night, and every night I had to help myself with a page of notes to
keep from getting myself mixed. The notes consisted of beginnings of
sentences, and were eleven in number, and they ran something like this:

"IN THAT REGION THE WEATHER--"

"AT THAT TIME IT WAS A CUSTOM--"

"BUT IN CALIFORNIA ONE NEVER HEARD--"

Eleven of them. They initialed the brief divisions of the lecture and
protected me against skipping. But they all looked about alike on the
page; they formed no picture; I had them by heart, but I could never
with certainty remember the order of their succession; therefore I
always had to keep those notes by me and look at them every little
while. Once I mislaid them; you will not be able to imagine the terrors
of that evening. I now saw that I must invent some other protection. So
I got ten of the initial letters by heart in their proper order--I,
A, B, and so on--and I went on the platform the next night with these
marked in ink on my ten finger-nails. But it didn't answer. I kept track
of the figures for a while; then I lost it, and after that I was never
quite sure which finger I had used last. I couldn't lick off a letter
after using it, for while that would have made success certain it also
would have provoked too much curiosity. There was curiosity enough
without that. To the audience I seemed more interested in my fingernails
than I was in my subject; one or two persons asked me afterward what was
the matter with my hands.

It was now that the idea of pictures occurred to me; then my troubles
passed away. In two minutes I made six pictures with a pen, and they did
the work of the eleven catch-sentences, and did it perfect