So long as the extreme parties are but a small portion, and the distribution of variation is normal, most in the middle course and thinning away to the upper and lower limits, the society is stable and benefits by its variations. But if the curve of variation is irregular, and shows two large groups with fewer in the middle course between them, the condition is dangerous. We had such a condition in England in the seventeenth century, and after a long struggle of each group to capture the middle party, the separation into two communities took place. The spiritual ancestors of Clifford and Perks and Byles were happy in their paradise of intolerant puritanism in New England, while Old England had internal peace for a couple of centuries. Another such process of fission now seems growing imminent, and it is again the question as to which group will capture the middle party. The positive danger of a diversity running into two separate groups is notorious in history. The Copts invited the Arab invasion to rid them of Byzantine bondage; the Britons invited the Saxons to save them from their neighbours. The ideals of a County Council which will not tolerate a quiet square in London, or of labour members who promote marches of the unemployed and unlimited taxation at their will, may drive the best thought in England to the tranquillity of a well-governed capital abroad; and as there are many people now who would prefer in England a Boer domination to that of the party represented by Cecil, Halifax, and Riley, so there are many others who would rather submit to a German government of London than to a sacking by a hungry mob. The segregation into two groups with an unstable link between them is fatal to the virtues classed as Patriotism. A studious Englishman would sooner have a Japanese or Russian professor for a neighbour, than have the average drinking workman and rowdy family who may be his distant cousins. And assuredly he would make no personal sacrifices to keep out of England any people who were proved to be the moral or intellectual superiors of the rest of his countrymen. We thus see that diversity, however great, must vary about a single centre, if it is to be favourable to society as a whole.