It has been necessary to consider the similarity theory, I have said, because it has eaten its way into all our thought.[14] Many people to-day seem to think that progress depends upon a number of people all speaking loudly together. The other day a woman said to me that she didn’t like the _Survey_ because it has on one page a letter from a conservative New York banker and on another some radical proposal for the reconstruction of society; she said she preferred a paper which took one idea and hammered away on that. This is poor psychology. It is the same reasoning which makes people think that certain kindred souls should come together, and then by a certain intensified thinking and living together some noble product will emerge for the benefit of the world. Such association is based on a wrong principle. However various the reasons given for the non-success of such experiments as Brook Farm, certain religious associations, and certain artistic and literary groups who have tried to live together, the truth is that most of them have died simply of non-nutrition. The bond created had not within it the variety which the human soul needs for its nourishment. Unity, not uniformity, must be our aim. We attain unity only through variety. Differences must be integrated, not annihilated, nor absorbed.[15] Anarchy means unorganized, unrelated difference; coördinated, unified difference belongs to our ideal of a perfect social order. We don’t want to avoid our adversary but to “agree with him quickly”; we must, however, learn the technique of agreeing. As long as we think of difference as that which divides us, we shall dislike it; when we think of it as that which unites us, we shall cherish it. Instead of shutting out what is different, we should welcome it because it is different and through its difference will make a richer content of life. The ignoring of differences is the most fatal mistake in politics or industry or international life: every difference that is swept up into a bigger conception feeds and enriches society; every difference which is ignored feeds _on_ society and eventually corrupts it. Heterogeneity, not homogeneity, I repeat, makes unity. Indeed as we go from groups of the lower types to groups of the higher types, we go from those with many resemblances to those with more and more striking differences. The higher the degree of social organization the more it is based on a very wide diversity among its members. The people who think that London is the most civilized spot in the world give as evidence that it is the only city in which you can eat a bun on a street corner without being noticed. In London, in other words, difference is expected of us. In Boston you cannot eat a bun on the street corner, at least not without unpleasant consequences.