Traces of amalgamation of religions--Instances elsewhere--Essential differences of Islam and Christianity--Compromise attempted--Influence of Islam, over Christianity--Innovating spirit in Spain--Heresy in Septimania--Its possible connection with Mohammedanism--Migetian heresy as to the Trinity--Its approach to the Mohammedan doctrine--Other similar heresies--Adoptionism--Our knowledge of it--Whence derived--Connection with Islam--Its author or authors--Probably Elipandus--His opponents--His character--Independence--Jealousy of the Free Church in the North--Nature of Adoptionism--Not a revival of Nestorianism---Origin of the name--Arose from inadvertence--Felix--His arguments--Alcuin's answers--Christ, the Son of God by adoption--Unity of Persons acknowledged--First mention of theory--Adrian---Extension of heresy--Its opponents--Felix amenable to Church discipline--Elipandus under Arab rule--Councils--Of Narbonne--Friuli--Ratisbon--Felix abjures his heresy--Alcuin--Council of Frankfort--Heresy anathematized--Councils of Rome and Aix--Felix again recants--Alcuin's book--Elipandus and Felix die in their error--Summary of evidence connecting adoptionism with Mohammedanism--Heresy of Claudius---Iconoclasm Libri Carolini--Claudius, bishop of Turin--Crusade against image-worship--His opponents--Arguments--Independence--Summoned before a Council--Refuses to attend--Albigensian heresy 114-136 CHAPTER X. Mutual influences of the two creeds--Socially and intellectually--"No monks in Islam"--Faquirs--The conventual system adopted by the Arabs--Arab account of a convent--Moslem nuns--Islam Christianised---Christian spirit in Mohammedanism--Arab magnanimity--Moslem miracles---like Christian ones--Enlightened Moslems--Philosophy--Freethinkers--Theologians--Almanzor--Moslem sceptics--Averroes--The faquis or theologians--Sect of Malik ibn Ans--Power of theologians---Decay of Moslem customs--Wine drunk--Music cultivated--Silk worn--Statues set up--Turning towards Mecca--Eating of sow's flesh--Enfranchisement of Moslem women--Love--Distinguished women---Women in mosques--At tournaments--Arab love-poem--Treatise on love 136-149 CHAPTER XI. Influence of Mohammedanism--Circumcision of Christians--Even of a bishop--Customs retained for contrast--Cleanliness rejected as peculiar to Moslems--Celibacy of clergy--Chivalry--Origin--Derived from Arabs--Favoured by state of Spain--Spain the cradle of chivalry--Arab chivalry--Qualifications for a knight--Rules of knighthood--The Cid--Almanzor--His generosity--Justice--Moslem military orders--Holy wars--Christianity Mohammedanized--The "Apotheosis of chivalry"--Chivalry a sort of religion--Social compromise--Culminates in the Crusades 149-156 APPENDICES. APPENDIX A.