nciple is called: "The Materialistic
Conception of History." It is not mentioned by name in the
manifesto, but it is there like a living presence spreading
light in dark places of history which had never been penetrated
by previous thinkers. The key to all history is found in methods
of producing and distributing material wealth. Out of the
changes in this field all other social changes come.

Forty years later Frederick Engels gave completeness to the
Manifesto by adding a preface which defines the main theory,
gives an estimate of its value, and explains his part as
co-author with Marx.

No other book can ever take the place of the Communist
Manifesto. Its value grows with the passing years. It was the
first trumpet blast to announce the coming of the triumphant
proletariat.

The Manifesto's first two chapters and its closing paragraph are
beyond all price. They are without parallel in the literature of
the world. They sparkle like "jewels on the stretched forefinger
of all time."

Here the speaker may show the book and state its price, and proceed with
the selling. If the sale is made while the audience is leaving, nothing
further need be said, and if the sale is the last thing in the meeting
it is useless to ask the audience to remain seated during the sale. They
get irritated and the meeting breaks up in confusion. See that your
salesmen are posted at the exits where they will face the audience as it
leaves. At one big meeting in Pittsburg where the sales of a fifty cent
book reached over sixty dollars they would have been double but some of
the sellers came to the front, and while the audience was clamoring for
books which could not be had at the doors, these sellers were following
the audience in the rear with armfuls which they had no chance to sell.

If the sale is made before the lecture while the sellers are passing
through the audience the speaker should continue speaking of the book so
as to sustain interest. There will be no loss of time making change if
the right priced books are sold. 10c, 25c, 50c or $1 are right prices.
At a public meeting it is a mistake to try to sell a book at an odd
price as 15c or 35c or 60c. The demand dies and the audience gets
impatient while the sellers are trying to make change.

The speaker who endeavors to make a success of book-selling at his
meetings will find his labors doubled. The larger his