Miracles are built into nature

 Rambam (Shemoneh Perachim 8) This occasioned the sages to say that all miracles which deviate from the natural course of events, whether they have already occurred, or, according to promise, are to take place in the future, were fore-ordained by the Divine Will during the six days of creation, nature being then so constituted that those miracles which were to happen really did afterwards take place. Then, when such an occurrence happened at its proper time, it may have been regarded as an absolute innovation, whereas in reality it was not. The Rabbis expatiate very much upon this subject in the Midrash Koheleth and in other writings, one of their statements in reference to this matter being, (Avodah Zarah 54b) "Everything follows its natural course". In everything that they said, you will always find that the Rabbis (peace be unto them!) avoided referring to the Divine Will as determining a particular event at a particular time. When, therefore, they said that man rises and sits down in accordance with the will of God, their meaning was that, when man was first created, his nature was so determined that rising up and sitting down were to be optional to him; but they as little meant that God wills at any special moment that man should or should not get up, as He determines at any given time that a certain stone should or should not fall to the ground. The sum and substance of the matter is, then, that thou shouldst believe that just as God willed that man should be upright in stature, broad-chested, and have fingers, likewise did He will that man should move or rest of his own accord, and that his actions should be such as his own free will dictates to him, without any outside influence or restraint, which fact God clearly states in the truthful Law, which elucidates this problem, when it says, (Genesis 3:22) "Behold, the man is become as one of us to know good and evil". The Targum, in paraphrasing this passage, explains the meaning of the words "mimmenu lada'at tov vara". Man has become the only being in the world who possesses a characteristic which no other being has in common with him. What is this characteristic? It is that by and of himself man can distinguish between good and evil, and do that which he pleases, with absolutely no restraint. Since, then, this is so, it would have even been possible for him to have stretched out his hand, and, taking of the tree of life, to have eaten of its fruit, and thus live forever. Since it is an essential characteristic of man's makeup that he should of his own free will act morally or immorally, doing just as he chooses, it becomes necessary to teach him the ways of righteousness, to command and exhort him, to punish and reward him according to his deserts. It behooves man also to accustom himself to the practice of good deeds, until he acquires the virtues corresponding to those good deeds; and, furthermore, to abstain from evil deeds so that he may eradicate the vices that may have taken root in him. Let him not suppose that his characteristics have reached such a state that they are no longer subject to change, for any one of them may be altered from the good to the bad, and vice versa; and, moreover, all in accordance with his own free will. To confirm this theory, we have mentioned all these facts concerning the observances and the transgressions of the Law.