Related to this quality of duration, but still distinguishable from it, is the depth of the causes from which the social mind emanates. The cause, at least the immediate one, may be very superficial, a mere trivial incident, but it may develop a permanent aspect of the social mind.

In my practice class the children would play with their ink wells when I was not watching. One day Gladys tipped the ink all over her new dress. That trouble has practically ceased.

In a certain small town some of the people held a critical attitude toward the teacher. One day one of the children fell and cut his head quite badly. The teacher dressed the wound and sent the child home. That evening she called at the house. That was the beginning of chats at gateways and other calls in which teacher and people met. Soon the attitude toward the teacher was entirely different.

A teacher had considerable difficulty with discipline; the boys were continually in mischief. One day one of the older boys took a paper wad, dipped it in ink, and fired it at the teacher. It hit squarely on the front of her white shirt waist, making a huge spot of ink. The room was still as death; the pupils expected to see the teacher fly into a rage. But instead she stood perfectly calm and went on with the reading lesson as though nothing had happened. It was such an impressive lesson to those boys, showing them her dignity and power, that they never gave her any more trouble but rather became a help.

In the last two cases, though the occasion of the change in the social mind was superficial, the cause was really fundamental: the character of the teacher was there all the time, but some appropriate incident had to come to make it evident. So also probably in the following case, although the circumstances are not given:

At one time the principal of the high school I attended was a good-looking man who also taught well, so that every one had a good opinion of him, the town people as well as the students. Later in the year, however, he displeased them very much and he then seemed just the opposite of what he did at the beginning of the year. This shows the transient nature of popular impression.