July 14, 1909.  Yesterday’s dispute resumed, I still maintaining that, whereas we can think, we generally don’t do it.  Don’t do it, & don’t have to do it:  we are automatic machines which act unconsciously.  From morning till sleeping-time, all day long.  All day long our machinery is doing things from habit & instinct, & without requiring any help or attention from our poor little 7-by-9 thinking apparatus.  This reminded me of something:  thirty years ago, in Hartford, the billiard-room was my study, & I wrote my letters there the first thing every morning.  My table lay two points off the starboard bow of the billiard-table, & the door of exit and entrance bore northeast&-by-east-half-east from that position, consequently you could see the door across the length of the billiard-table, but you couldn’t see the floor by the said table.  I found I was always forgetting to ask intruders to carry my letters down-stairs for the mail, so I concluded to lay them on the floor by the door; then the intruder would have to walk over them, & that would indicate to him what they were there for.  Did it?  No, it didn’t.  He was a machine, & had habits.  Habits take precedence of thought.

Now consider this:  a stamped & addressed letter lying on the floor —­lying aggressively & conspicuously on the floor—­is an unusual spectacle; so unusual a spectacle that you would think an intruder couldn’t see it there without immediately divining that it was not there by accident, but had been deliberately placed there & for a definite purpose.  Very well—­it may surprise you to learn that that most simple & most natural & obvious thought would never occur to any intruder on this planet, whether he be fool, half-fool, or the most brilliant of thinkers.  For he is always an automatic machine & has habits, & his habits will act before his thinking apparatus can get a chance to exert its powers.  My scheme failed because every human being has the habit of picking up any apparently misplaced thing & placing it where it won’t be stepped on.

My first intruder was George.  He went and came without saying anything.  Presently I found the letters neatly piled up on the billiard-table.  I was astonished.  I put them on the floor again.  The next intruder piled them on the billiard-table without a word.  I was profoundly moved, profoundly interested.  So I set the trap again.  Also again, & again, & yet again—­all day long.  I caught every member of the family, & every servant; also I caught the three finest intellects in the town.  In every instance old, time-worn automatic habit got in its work so promptly that the thinking apparatus never got a chance.

I do not remember this particular discussion, but I do distinctly recall being one of those whose intelligence was not sufficient to prevent my picking up the letter he had thrown on the floor in front of his bed, and being properly classified for doing it.