Wisdom of yore. What works for you?

When I run across an old song, film, or quote that really seems to stand the test of time I’m often conflicted. On the one hand I’m impressed with the wisdom of the person or persons behind the work. On the other hand, I’m discouraged because the truisms they reveal still seem like revelations rather than common knowledge. (For me, a few films in this category are A Face in the Crowd and Meet John Doe.)

In the field of marketing and persuasion from a bygone era, I give you these examples of virually untarnished relevance. Any guesses on the author?

Even in a basic sense, business is becoming dependent on public opinion. …Business must express itself and its entire corporate existence so that the public will understand and accept it. It must dramatize its personality and interpret its objectives in every particular in which it comes into contact with the community (or the nation) of which it is a part.

And

It was one of the doctrines of the reaction psychology that a certain stimulus often repeated would create a habit, or that the mere reiteration of an idea would create a conviction.

And

…the group mind does not think in the strict sense of the word. In place of thoughts, it has impulses, habits, and emotions. In making up its mind, its first impulse is usually to follow the example of a trusted leader.

What stands the test of time for you?