Throughout the centuries pantheistic and animistic forms of mysticism have found many adherents among the Mohammedans; but the infallible Agreement has persisted in calling that heresy. Ethical mysticism, since Ghazâlî, has been fully recognized; and, with law and dogma, it forms the sacred trio of sciences of Islâm, to the study of which the Arabic humanistic arts serve as preparatory instruments. All other sciences, however useful and necessary, are of this world and have no value for the world to come. The unfaithful appreciate and study them as well as do the Mohammedans; but, on Mohammedan soil they must be coloured with a Mohammedan hue, and their results may never clash with the three religious sciences. Physics, astronomy, and philosophy have often found it difficult to observe this restriction, and therefore they used to be at least slightly suspected in pious circles.

Mysticism did not only owe to Ijmâ' its place in the sacred trio, but it succeeded, better than dogmatics, in confirming its right with words of Allah and His Prophet. In Islâm mysticism and allegory are allied in the usual way; for the illuminati the words had quite a different meaning than for common, every-day people. So the Qorân was made to speak the language of mysticism; and mystic commentaries of the Holy Book exist, which, with total disregard for philological and historical objections, explain the verses of the Revelation as expressions of the profoundest soul experiences. Clear utterances in this spirit were put into the Prophet's mouth; and, like the canonists, the leaders on the mystic Way to God boasted of a spiritual genealogy which went back to Mohammed. Thus the Prophet is said to have declared void all knowledge and fulfillment of the law which lacks mystic experience.

Of course only "true" mysticism is justified by Ijmâ' and confirmed by the evidence of Qorân and Sunnah; but, about the bounds between "true" and "false" or heretical mysticism, there exists in a large measure the well-known diversity of opinion allowed by God's grace. The ethical mysticism of al-Ghazâlî is generally recognized as orthodox; and the possibility of attaining to a higher spiritual sphere by means of methodic asceticism and contemplation is doubted by few. The following opinion has come to prevail in wide circles: the Law offers the bread of life to all the faithful, the dogmatics are the arsenal from which the weapons must be taken to defend the treasures of religion against unbelief and heresy, but mysticism shows the earthly pilgrim the way to Heaven.

It was a much lower need that assured the cult of saints a place in the doctrine and practice of Islâm. As strange as is Mohammed's transformation from an ordinary son of man, which he wanted to be, into the incarnation of Divine Light, as the later biographers represent him, it is still more astounding that the intercession of saints should have become indispensable to the community of Mohammed, who, according to Tradition, cursed the Jews and Christians because they worshipped the shrines of their prophets. Almost every Moslim village has its patron saint; every country has its national saints; every province of human life has its own human rulers, who are intermediate between the Creator and common mortals. In no other particular has Islâm more fully accommodated itself to the religions it supplanted. The popular practice, which is in many cases hardly to be distinguished from polytheism, was, to a great extent, favoured by the theory of the intercession of the pious dead, of whose friendly assistance people might assure themselves by doing good deeds in their names and to their eternal advantage.

The ordinary Moslim visitor of the graves of saints does not trouble himself with this ingenious compromise between the severe monotheism of his prophet and the polytheism of his ancestors. He is firmly convinced, that the best way to obtain the satisfaction of his desire after earthly or heavenly goods is to give the saint whose special care these are what he likes best; and he confidently leaves it to the venerated one to settle the matter with Allah, who is far too high above the ordinary mortal to allow of direct contact.

In support even of this startling deviation from the original, traditions have been devised. Moreover, the veneration of human beings was favoured by some forms of mysticism; for, like many saints, many mystics had their eccentricities, and it was much to the advantage of mystic theologians if the vulgar could be persuaded to accept their aberrations from normal rules of life as peculiarities of holy men. But Ijmâ' did more even than tradition and mysticism to make the veneration of legions of saints possible in the temples of the very men who were obliged by their ritual law to say to Allah several time daily: "Thee only do we worship and to Thee alone do we cry for help."

In the tenth century of our era Islâm's process of accommodation was finished in all its essentials. From this time forward, if circumstances were favourable, it could continue the execution of its world conquering plans without being compelled to assimilate any more foreign elements. Against each spiritual asset that another universal religion could boast, it could now put forward something of a similar nature, but which still showed characteristics of its own, and the superiority of which it could sustain by arguments perfectly satisfactory to its followers. From that time on, Islâm strove to distinguish itself ever more sharply from its most important rivals. There was no absolute stagnation, the evolution was not entirely stopped; but it moved at a much quieter pace, and its direction was governed by internal motives, not by influences from outside. Moslim catholicism had attained its full growth.

We cannot within the small compass of these lectures consider the excrescences of the normal Islâm, the Shî'itic ultras, who venerated certain descendants of Mohammed as infallible rulers of the world, Ishma'ilites, Qarmatians, Assassins; nor the modern bastards of Islâm, such as the Sheikhites, the Bâbî's, the Behâ'îs—who have found some adherents in America—and other sects, which indeed sprang up on Moslim soil, but deliberately turned to non-Mohammedan sources for their inspirations. We must draw attention, however, to protests raised by certain minorities against some of the ideas and practices which had been definitely adopted by the majority.

In the midst of Mohammedan Catholicism there always lived and moved more or less freely "protestant" elements. The comparison may even be continued, with certain qualifications, and we may speak also of a conservative and of a liberal protestantism in Islâm. The conservative Protestantism is represented by the Hanbalitic school and kindred spirits, who most emphatically preached that the Agreement (Ijmâ') of every period should be based on that of the "pious ancestors." They therefore tested every dogma and practice by the words and deeds of the Prophet, his contemporaries, and the leaders of the Community in the first decades after Mohammed's death. In their eyes the Church of later days had degenerated; and they declined to consider the agreement of its doctors as justifying the penetration into Islâm of ideas and usages of foreign origin. The cult of saints was rejected by them as altogether contradictory to the Qorân and the genuine tradition. These protestants of Islâm may be compared to those of Christianity also in this respect, that they accepted the results of the evolution and assimilation of the first three centuries of Islâm, but rejected later additions as abuse and corruption. When on the verge of our nineteenth century, they tried, as true Moslims, to force by material means their religious conceptions on others, they were combated as heretics by the authorities of catholic Islâm. Central and Western Arabia formed the battlefield on which these zealots, called Wahhâbites after their leader, were defeated by Mohammed Ali, the first Khedive, and his Egyptian army. Since they have given up their efforts at violent reconstitution of what they consider to be the original Islâm, they are left alone, and their ideas have found adherents far outside Arabia, e.g., in British India and in Northern and Central Africa.

In still quite another way many Moslims who found their freedom of thought or action impeded by the prevailing law and doctrine, have returned to the origin of their religion. Too much attached to the traditions of their faith, deliberately to disregard these impediments, they tried to find in the Qorân and Tradition arguments in favour of what was dictated to them by Reason; and they found those arguments as easily as former generations had found the bases on which to erect their casuistry, their dogma, and their mysticism. This implied an interpretation of the oldest sources independent from the catholic development of Islâm, and in contradiction with the general opinion of the canonists, according to whom, since the fourth or fifth century of the Hijrah, no one is qualified for such free research. A certain degree of independence of mind, together with a strong attachment to their spiritual past, has given rise in the Moslim world to this sort of liberal protestantism, which in our age has many adherents among the Mohammedans who have come in contact with modern civilization.