Johann Wolfgang Goethe, Noten und Abhandlungen zum Weststlichen Dvan, WA I, 7, 32; translator unknown
My choice of Muhammad to lead the list of the world’s most influential person may surprise some readers and may be questioned by others, but he was the only man in history who was supremely successful on both the religious and secular levels. It is probable that the relative influence of Muhammad on Islam has been larger than the combined influence of Jesus Christ and St. Paul on Christianity. Furthermore, Muhammad (unlike Jesus) was a secular as well as religious leader. In fact, as the driving force behind the Arab conquests, he may well rank as the most influential political leader of all time. It is this unparalleled combination of secular and religious influence, which I feel, entitles Muhammad to be considered the most influential single figure in human history.
Michael H. Hart, who in his book The 100 : A Ranking of the Most Influential Persons in History (1978) placed Muhammad in the first position, p. 33
He spoke in the market and other public places. Most of those who heard him laughed at what he told them; but some poor people and a few slaves believed him and adopted the new religion. Others said he was a dreamer and a fool.
Mohammed, however, paid no heed to the insults he received. He went on telling about the appearance of Gabriel and preaching the doctrines which he said the angel had ordered him to teach the people.
John Henry Haaren, in Famous Men of the Middle Ages (1904)
The league of nations founded by the prophet of Islam put the principle of international unity and human brotherhood on such universal foundations as to show candle to other nations. … the fact is that no nation of the world can show a parallel to what Islam has done towards the realization of the idea of the League of Nations.
Christiaan Snouck Hurgronje, as quoted in Encyclopaedic Survey of Islamic Culture (1997) by Mohamed Taher, p. 260
Never has a man set for himself, voluntarily or involuntarily, a more sublime aim, since this aim was super human; to subvert superstitions which had been imposed between man and his Creator, to render God unto man and man unto God; to restore the rational and sacred idea of divinity amidst the chaos of the material and disfigured gods of idolatry, then existing. Never has a man undertaken a work so far beyond human power with so feeble means, for he Muhammad had in the conception as well as in the execution of such a great design, no other instrument than himself and no other aid except a handful of men living in a corner of the desert. Finally, never has a man accomplished such a huge and lasting revolution in the world, because in less than two centuries after its appearance, Islam, reigned over the whole of Arabia, and conquered, in God’s name, Persia, Khorasan, Transoxania, Western India, Syria, Egypt, Abyssinia, all the known continent of Northern Africa, numerous islands of the Mediterranean Sea, Spain and part of Gaul.
If greatness of purpose, smallness of means, and astounding results are the three criteria of human genius, who could dare to compare any great man in modern history with Muhammad? The most famous men created arms, laws and empires only. They founded, if anything at all, no more than material powers which often crumbled away before their eyes. This man moved not only armies, legislations, empires, peoples and dynasties, but millions of men in one-third of the then inhabited world; and more than that, he moved the altars, the gods, the religions, the ideas, the beliefs and souls. . . his forbearance in victory, his ambition, which was entirely devoted to one idea and in no manner striving for an empire; his endless prayers, his mystic conversations with God, his death and his triumph after death; all these attest not to an imposture but to a firm conviction which gave him the power to restore a dogma. This dogma was twofold, the unity of God and the immateriality of God; the former telling what God is, the latter telling what God is not; the one overthrowing false gods with the sword, the other starting an idea with words.
Philosopher, orator, apostle, legislator, warrior, conqueror of ideas, restorer of rational dogmas, of a cult without images; the founder of twenty terrestrial empires and of one spiritual empire, that is Muhammad. As regards all standards by which human greatness may be measured, we may well ask, is there any man greater than he?
Alphonse de Lamartine, Histoire de la Turquie (1854), Vol. II, pp. 276-277