mounted in order to find out if it resembled the cacti of Arizona. As he gazed at the little plant, he noticed that it was growing close to the east side of the trail (he was then traveling toward the southwest), and that only a short distance south from where the cactus was growing was another trail bearing to the northwest. On his return journey he was uncertain as to whether he should take the trail bearing to the northwest or the one to the northeast, but as soon as he saw the cactus over on the east side of the trail leading to the north-east, he knew that was the road for him to take. This proved a valuable lesson to him regarding the advisability of paying attention.
The rule of Attention far excels in serviceableness any other rules that have ever been put forward by any other system of memory training, be-
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