In this second installment of the correspondence between Ibn Sina and al-Biruni, which is being serialized in Islam & Science, Ibn Sina responds to four questions raised by al-Biruni. The first of these four is a criticism of Aristotle for his over-reliance on the views of the ancients concerning heaven. The second deals with Aristotle's view that there are only six directions to space. The third pertains to the issue of continuity and discontinuity of physical bodies and the fourth is about the Peripatetics' denial of the possibility of the existence of another world completely different from the one we know.
Keywords: Ibn Sina-al-Biruni correspondence; criticism of Aristotle's reliance on the views of the ancients; notion of six directions of space; continuity and discontinuity of physical bodies.
15. The second question: Why did Aristotle consider the views of the ancients and predecessors concerning the heaven and their finding [the celestial bodies] to be just as how he found them to be, a strong argument for immutability and perpetuity of the heaven? Anyone who is not stubborn and does not insist on falsehood would agree that this is not a known [fact]. We do not know more [about the celestial bodies] than what has been reported by the people of the Book as well as by Indians and other nations like them, appears to be false upon investigation. This is because of the continuous changes [which occur] on the surface of earth, [changes] that occur in increments or all at once. Likewise, the obvious alterations in the state of mountains since antiquity is proof of events resulting in changes.
16. The answer: You should know that [Aristotle] did not give [the views of the ancients] as an evidence; it was only something that came by way of speech which he mentioned at two places. [Further], the case of mountains does not apply to the celestial sphere; even if nations witnessed mountains preserved in their totality, [this observation] does not disclose changes resulting from the action of the elements on their different parts, some of which are collapsing and folding upon one another, and some of which are altering their shapes and undergoing other changes beyond these--changes which have been mentioned by Plato in his book Fi Siyasat as well as in other books. It is as if you have taken this objection from John Philoponos, who was opposed to Aristotle, simply because he himself was a Christian. However, whoever reads his commentary on generation and corruption and his other books would find that he agrees with Aristotle on this issue. Or [you may have derived your arguments] from Muhammad ibn Zakariyyab al-Razi, who meddles in metaphysics and exceeds his competence. He should have remained confined to surgery and to urine and stool testing--indeed he exposed himself and showed his ignorance in these matters. And you should also know that when Aristotle said "the universe has no beginning" he did not mean that the universe did not have a Creator; rather, he intended to exalt and protect the Creator from the charge of inaction, but this is not the place to discuss this.
17. And as for your saying, "anyone who is not stubborn and who does not insist on falsehood": this is an ugly and rude insult--either you comprehended the saying of Aristotle in this matter or you did not. If you did not, your belittling of someone who said something beyond your grasp is inappropriate. And if you did understand, your comprehension of the meaning should have prevented you from dragging in this quarrel; for your pursuit of what your intelligence prevents you from pursuing is inappropriate.
18. The third question: Why do [Aristotle] and others say that there are only six directions to space? Their example is that of the cube, for which the six directions have parallels. If we add to these six tangent cubes, so that when the spaces are all filled in, there will be 27 cubes which will all be touching the first cube from angles and sides. …