The First: If a person grasps the basic principles of a science and recognizes its essential usefulness and employs its proficiently where he should, and constructs his cause on it, this is evidence of his skill and expertise in that science.
The Second Point: If you are cognizant of human nature [you know that] you will never see a person being so bold as to oppose [the majority] without hesitation or concern or constraint, or to lie even if insignificantly, among a people even if they are few, for a cause even if lowly, with dignity even if small. So how could someone – with the utmost dignity, for a cause of the utmost gravity, among people who were extremely numerous, in the face of extreme obstinacy despite his being unlettered – how could he speak of matters unattainable by reason alone and disclose them with the greatest seriousness and proclaim them over the heads of witnesses? Does this not point to his truthfulness, and that [what he proclaimed] was not from him but from Allah?
The Third: There are many sciences that for the civilized are axiomatic and teach customs, events, situations, and actions, but that are unknown and theoretical to [primitive] nomads. So if someone wants to interrogate [them] and investigate their circumstances, especially in past centuries, he has to imagine himself among them in those deserts.
The Fourth: This is that if a person debates with experts in a science, even if it is only grammar, and propounds his views concerning the matters it entails, corroborating what is agreed upon and correcting points of dispute, would this not demonstrate to you his superiority and that his knowledge is God-given (wahbī)?
If you have understood these points, understand now that despite his being unlettered, Muhammad the Arabian (Upon whom be peace) recounts to us through the tongue of the Qur’an the stories of the prophets and early times as though he had been present and witnessed them. He describes their exploits and divulges their secrets to all the world in the way of a mighty cause that has attracted the attention of intelligent men. He recounts these without concern, for he took their vital points and fundamental principles as the basis of his own cause, confirming matters unanimously endorsed by the previous scriptures and correcting matters of difference. As though with a fleet spirit reflecting divine revelation he traversed time and space and entered the depths of the past, then proclaimed [what was there] as though he had witnessed it. Thus, his doing this is a proof of his prophethood and one of his miracles. All the evidences of the prophethoods of the previous