X commodity A=y commodity B essentially differs from the equation

y Commodity B=X Commodity A.

Now, a discussion whether there is between these two equations a difference which it is Socially necessary to take account of, is a thing to be put into books where it can be skipped, and not imposed in cold blood even on intellectual enemies.  Personally I do not believe there is, for I do not think that Social phenomena can be dealt with by the rigorous methods of mathematics.  One can never be sure that the unknown quantities are all accounted for.  But whether this or similar propositions are essential to the discussion of the theory of surplus value or not, I do not describe them because they are of no particular importance.

Socialism is not based upon the Marxian theory of value, but the Marxian theory of value was evolved in an endeavor to fix a scientific basis for a popular movement already fully under way.  Socialism is not based on reason, but emotion; not on reflection, but desire; it is not scientific, but popular.  If every Socialist on earth should concede that the Marxian theory of surplus value had been knocked into smithereens, it would have no more effect on the progress of Socialism than the gentle zephyr of a June day on the hide of a rhinoceros.  Socialism must be attacked in the derived propositions about which popular discussion centers, and the assault must be, not to prove that the doctrines are scientifically unsound, but that they tend to the impoverishment and debasement of the masses.  These propositions are three, and I lay down as my thesis — for I abhor defensive warfare — that

Rent is right,
Interest is right,
Profits are right,

and that they are all three ethically and economically justified, and are in fact essential to the happiness and progress of the race, and more especially to those who labor with their hands.

Now, first, rent:  I confess that I have no patience with any one who claims, as an inherent right, the exclusive ownership of any part of the earth.  He might as well claim ownership in a section of air.  In this I am very certain that I have the hearty concurrence of every member of this Club.  I am so sure of this, in fact, that I am going to make that assumption, in which we all agree, the starting point of a little dialogue, in which, after the manner of Plato, I will put Socrates at one end of the discussion, and some of his friends, whom we will suppose to be Phaedo, and Crito, and Simmias, and the rest at the other, and we will let Socrates and Phaedo carry on the conversation, which might run as follows: 

Socrates — We are agreed, then, that no man has any right inherent in himself to the ownership of land.

Phaedo — Certainly, we agree to that.  Such a thing is absurd, for the earth is a gift to the human race, and not to particular men.

Socrates — I am glad that you think so, and am sure we shall continue to agree.  And if no one man has any right to exclusive ownership of land, neither have any two men, since it is plain that neither could convey to himself and another any right which he did not possess, nor could two men together by any means get lawful title to what neither was entitled to hold.