Ramban (Bereishis 46:15) But Rabbi Abraham ibn Ezra replied, saying that “this is surprising. For if so, why did Scripture not mention the wonder that befell her, for she gave birth to Moses when she was one hundred and thirty years old? And why did it mention the case of Sarah who gave birth when she was ninety years old? This distress was not yet sufficient for us so that the poets came and composed liturgic poems for the day of Simchath Torah, wherein they state, ‘Jochebed, my mother, will be comforted after me,’ [implying that Jochebed survived her son], and thus she was two hundred and fifty years old at the death of Moses! Is the proof of the poets for this longevity of Jochebed because Ahijah the Shilonite lived a life of great duration? [If so, this is not a proof, for his longevity is but] an Agadic tradition or the opinion of a single authority.” These are the words of Rabbi Abraham ibn Ezra.
Now lest he be wise in his own eyes in contradicting the words of our Rabbis,
I must answer him and say that in any case, there is in the matter of Jochebed a great wonder of the hidden miracles which constitute the foundation of the Torah. Jochebed was Levi’s actual daughter, and not merely his offspring, as it is written, Jochebed, the daughter of Levi, whom [her mother] bore to Levi, and it is furthermore written, And Amram took himself Jochebed his father’s sister for a wife. [Thus Amram, Levi’s grandson, married Jochebed, Levi’s daughter.] Now if we would say that Levi begot Jochebed in his younger years, just as he begot all his sons, this would place her birth soon after his descent into Egypt, and she would have been very old at the time of Moses’ birth, at or near the age stated by our Rabbis. And if we would say that he begot her after he resided in Egypt for many years — say, for a period of fifty-seven years — then Levi would have been one hundred years old at Jochebed’s birth, for when he went down to Egypt he was forty-three years of age. In that case, there were two great wonders! [Levi, at the time he begot Jochebed], was as old as Abraham, concerning whom Scripture mentions, Shall a child be born to him who is a hundred years old? and it is further written, And my lord is old also, while Jochebed would still have been an elderly woman of seventy-three when Moses was born! And should we further postpone Jochebed’s birth to the end of Levi’s days, the wonder of his begetting a child will be greater than that of Abraham!
But I will tell you a true principle, clearly indicated in the Torah. Scripture mentions miracles performed through a prophet and which he previously prophesied, or performed by an angel who is revealed in the course of a Divine mission, but those effected naturally in order to help the righteous or destroy the wicked are not mentioned in the Torah or in the books of the prophets.
May this be “hot gold poured into the mouth” of this wise man who refuted the words of our Rabbis in the matter of Phinehas and similar matters in many places.
Why should Scripture mention hidden miracles when all the foundations of the Torah are hidden miracles. In the entire scope of the Torah there are only miracles, and no nature or custom. All assurances of the Torah are in the form of signs and wonders, as it is not natural that he who has connection with one of the forbidden degrees of marriage or he who eats forbidden fat suffers excision or death. Nor is it by nature that the heavens become as iron because we have sowed our fields in the Sabbatical year. Similarly, all the assurances of the Torah concerning those blessings [which will result from our observance of the law], and all the good fortune of the righteous ones because of their righteousness, as well as all the prayers of our king David [in the book of Psalms] and all our prayers, all are founded upon miracles and wonders, except that there is no heralded change in the nature of the world, as I have already mentioned, and I will yet explain it further, with the help of G-d.
I will give you faithful testimony to that which I have said. We know that from the time Israel came into the Land until the birth of our lord David, about three hundred and seventy years elapsed. These years are to be divided among four generations: Salmon, Boaz, Obed, and Jesse [David’s father], each one being allotted ninety-three years. Thus when they begot children they were all approximately as old as Abraham was when he begot Isaac. Furthermore, each one begot his son in the year of his death, a most unusual thing, since in their era the general span of life was not a hundred years. And if one of them begot his son in his younger years, as is usual, the others would have had to be much older than Abraham, and thus the wonder concerning them would be exceedingly great since people in the generation of Abraham lived long, and in the days of David the average lifespan was reduced to a half. And perhaps these four generations lived longer than their contemporaries for it is possible that Salmon was already advanced in years when he entered the Land of Israel. It is for this reason that the masters of Tradition, who are the true Sages, have attributed longevity to Obed, this being a covert miracle which was done to the ancestor of the kingdom [of the house of David], the son of the righteous one [Ruth], who had come to take refuge under the wings of the Divine Presence. The Sages similarly mention longevity in connection with Obed’s mother, Ruth. Now I have already explained that the wonder in the case of Abraham was not as the above-mentioned Sage [Rabbi Abraham ibn Ezra] and other masters of the Scriptures have thought. Abraham begot Isaac seventy-five years before his death, prior to the completion of two-thirds of his lifespan, and in all generations, old age does not affect people until three quarters of their lives have passed, just as the doctors have considered the divisions of life to be: childhood, youth, manhood, and old age. In these generations, when the lifespan is about seventy years, doctors do not consider a person aged until after sixty. Moreover, Abraham begot many children forty years after the birth of Isaac, and the wonder is thus manifoldly miraculous! And should we say that G-d caused Abraham to revert to his youthful days, it may be asked why Scripture does not mention this great wonder when it was an open and known miracle which is contrary to nature. Moreover, it is known that in this present generation some men beget children until they are full seventy or eighty years old and more, depending upon the extent to which they retain their natural vitality. Women also have no specific time [for ceasing to conceive], as long as they have their period they can give birth. However, the wonder in the case of Abraham and Sarah, as I explained there, was due to the fact that they had not begotten children in their younger years, and now together they begot a child. In the case of Sarah there was an additional wonder, i.e., that the manner of women had ceased with her, and after this happens, women no longer give birth. Now if Jochebed lived as many years as her father Levi had, and if her vitality remained with her until near her old age, as is the way of women, it would be no wonder if she gave birth at the time set forth by our Rabbis, [namely, at one hundred and thirty years of age]. It is because G-d wanted to redeem Israel though the brothers [Moses and Aaron], and since the time of the redemption had not yet come, He delayed their birth many years until their mother was old. Nothing is too difficult for the Eternal.