Making Sense of the Ten Plagues
Joseph Francis Alward
The following interpretation of the plague stories (Exodus 7-12) assumes that Pharaoh's vanity prevents him from admitting to himself or his people that the Lord's power is greater than his; this leads to increasingly more irrational behavior as plague after plague is brought down around him . The first three plagues involve a sort of contest between the Lord--with Moses and Aaron as his intermediaries--on one side, and Pharaoh and his magicians on the other. Where below we refer to the Lord having done something, it often will mean that the Lord gave Aaron or Moses the power to do it on his behalf.
The Blood Plague
In the first plague, the Lord turns all of Egypt's water to blood; but, before he undoes this act to reset the stage for the magicians to try the same thing , fish die and the water begins to stink. Because the magicians are also able to convert the waters to blood, Pharaoh returns to his house confident his magic is equal to that of the Lord and that his magicians will soon convert the blood back to water. Before the magicians do so, however, doubtful Egyptians begin digging for water.
The Frog Plague
Seven days later, the Lord brings up great quantities of frogs, but does not remove them. Pharaoh allows his magicians to match the Lord's trick by bringing up frogs, but they evidently cannot remove them. Pharaoh then begs Moses to ask the Lord to remove the frogs, and the Lord does so; once again, however, Pharaoh refuses to let the Jews go.
The Lice Plague and the Flies Plague
The Lord brings up lice everywhere. Pharaoh doubts his magicians can remove the lice, since they couldn't remove the frogs, but he lets them try to bring up lice anyway to try to show that his magicians have powers similar to the Lord's; if the magicians can't remove the lice, he'll just trick the Lord into removing them, just as he tricked him into removing the frogs. The magicians are unable to bring up lice.
Next, the Lord sends in swarms of flies, which he removes after Pharaoh promises to release the Hebrews; however, Pharaoh once again breaks his promise.
The Murrain Plague and the Boil Plague
The Lord now gives the Egyptian livestock a killing disease--murrain , and after several weeks all of the Egyptian livestock is dead. This is followed by a boil plague, but Pharaoh still won't let the Israelites go.
The Hail Plague
In the month following the end of the disease  the Egyptians acquire livestock from outside Egypt or from the Israelites; then the hail plague comes at the end of fall and kills the livestock and the vegetation. Pharaoh promises to release the Hebrews if the Lord will stop the hail. The Lord does so, but foolish Pharaoh, thinking he's bested the Lord once again, breaks his promise.
The Locust, Darkness, and First-Born Plagues
After a few winter months pass  the Lord launches a locust plague which consumes whatever was left in the field and on the trees after the hail plague. In return for a promise to release the Hebrews, the Lord sends the locust away, and Pharaoh once again refuses to let the Israelites leave. The plague of darkness lasting three days comes, but that's not enough to make Pharaoh relent, so the Lord kills every first-born in Egypt, sparing Israelites who show a sign of their faith by marking their houses with lamb's blood. Not a single house containing  an Egyptian first-born is spared, and Pharaoh--at long last--lets Moses' people go.
There are two problems with this account of the ten plagues. The first one is found in the first plague, where we assert that the Exodus author chose not to tell us what he may have felt was obvious: that the Lord, then later the magicians, reversed their water-to-blood conversions; the Lord made his reconversion in order to give the magicians a chance to try to match his feat, and the magicians made their reconversion in order to show that they could do what the Lord had done. One can argue that the author would have been aware that he was creating an obvious contradiction if he didn't believe--and expect the readers to infer--that there had to have been water for the Egyptians to try to convert to blood.
The second problem is in the last plague where Exodus 12:30 tells us that "there was not a house where there was not one dead". Since not every house has a living first-born (man or beast), the only way to harmonize this with the bible's statement is to assume (without much evidence) that the author was only referring to houses with first-born inside. There doesn't seem to be much support for this assertion; inerrantists will just have to live with this.
Flavius Josephus, a Jewish historian of the First Century AD, describes the ten plagues in the footnote below .
 Skeptics may object, saying that Exodus says nothing about the Lord converting the blood back to water in order to let the magicians try to convert all of Egypt's water to blood, just as the Lord had done. Well, some things don't have to be said. While it would have made more sense for the author to have explicitly told us of the reversal, perhaps he counted on the context of the story to lead to reader to infer what seems clearly obvious: if the Lord had not converted the blood back to water, there wouldn't have been any water for the magicians to try to convert. Furthermore, the reader has ample reason to infer that the reconversions had occurred, because the frogs plague came next, wherein live frogs came up from the river seven days later; if the river hadn't been converted back to water long before, the frogs would have been dead. Also, there wouldn't have been a need for a first-born plague (occurring at least 10 days later), because most of the Egyptians would have died of thirst (and the Israelites, too?), notwithstanding the hail plague; the melted waters from that plague would have mainly been reservoired in blood-contaminated streams, ponds, pool, and rivers. Thus, we have to make a choice: assume that the Exodus author was so dimwitted that he couldn't recognize he was constructing a contradiction, or else believe that he meant for us to infer that the reversals had occurred; another alternative is to believe that the author clumsily omitted important--but inferable--information.
 Murrain is a pestilence affecting animals and some vegetation.
 Skeptics may object, saying that there is no evidence that "a month" passed between the murrain plague and the hail plague, even though a boil plague intervened. However, there is no evidence that the time between the murrain and hail plagues had to be very short. Skeptics who insist without good evidence that the time was too short for any cattle to have been acquired by the Egyptians are just constructing a "how-it-could-have-been-a-contradiction" scenario. Farrell Till has made just such a claim; his views are presented--and rebutted--in Murrain and Hail Plagues.
 There is as much as six months available for the plagues. Assuming Moses just turned 80 when the plagues began, was 40 years exactly in the wilderness, and was just short of 120 and a half years old when he died, that leaves a half-year for the ten plagues.
 Exodus 12:30 says that "there was not a house where there was not one dead". This is a bit of clumsy writing on the part of the author; not every house in Egypt could have contained a first-born; he should have said that "there was not a house with a live first-born in it".
 Antiquities of the Jews by Flavius Josephus
Book II, Chapter 14
Concerning The Ten Plagues Which Came Upon The Egyptians
1. BUT when the king despised the words of Moses, and had no regard at all to them, grievous plagues seized the Egyptians; every one of which I will describe, both because no such plagues did ever happen to any other nation as the Egyptians now felt, and because I would demonstrate that Moses did not fail in any one thing that he foretold them; and because it is for the good of mankind, that they may learn this caution - Not to do anything that may displease God, lest he be provoked to wrath, and avenge their iniquities upon them. For the Egyptian river ran with bloody water at the command of God, insomuch that it could not be drunk, and they had no other spring of water neither; for the water was not only of the color of blood, but it brought upon those that ventured to drink of it, great pains and bitter torment. Such was the river to the Egyptians; but it was sweet and fit for drinking to the Hebrews, and no way different from what it naturally used to be. As the king therefore knew not what to do in these surprising circumstances, and was in fear for the Egyptians, he gave the Hebrews leave to go away; but when the plague ceased, he changed his mind again, end would not suffer them to go.
2. But when God saw that he was ungrateful, and upon the ceasing of this calamity would not grow wiser, he sent another plague upon the Egyptians: - An innumerable multitude of frogs consumed the fruit of the ground; the river was also full of them, insomuch that those who drew water had it spoiled by the blood of these animals, as they died in, and were destroyed by, the water; and the country was full of filthy slime, as they were born, and as they died: they also spoiled their vessels in their houses which they used, and were found among what they eat and what they drank, and came in great numbers upon their beds. There was also an ungrateful smell, and a stink arose from them, as they were born, and as they died therein. Now, when the Egyptians were under the oppression of these miseries, the king ordered Moses to take the Hebrews with him, and be gone. Upon which the whole multitude of the frogs vanished away; and both the land and the river returned to their former natures. But as soon as Pharaoh saw the land freed from this plague, he forgot the cause of it, and retained the Hebrews; and, as though he had a mind to try the nature of more such judgments, he would not yet suffer Moses and his people to depart, having granted that liberty rather out of fear than out of any good consideration. (35)
3. Accordingly, God punished his falseness with another plague, added to the former; for there arose out of the bodies of the Egyptians an innumerable quantity of lice, by which, wicked as they were, they miserably perished, as not able to destroy this sort of vermin either with washes or with ointments. At which terrible judgment the king of Egypt was in disorder, upon the fear into which he reasoned himself, lest his people should be destroyed, and that the manner of this death was also reproachful, so that he was forced in part to recover himself from his wicked temper to a sounder mind, for he gave leave for the Hebrews themselves to depart. But when the plague thereupon ceased, he thought it proper to require that they should leave their children and wives behind them, as pledges of their return; whereby he provoked God to be more vehemently angry at him, as if he thought to impose on his providence, and as if it were only Moses, and not God, who punished the Egyptians for the sake of the Hebrews: for he filled that country full of various sorts of pestilential creatures, with their various properties, such indeed as had never come into the sight of men before, by whose means the men perished themselves, and the land was destitute of husbandmen for its cultivation; but if any thing escaped destruction from them, it was killed by a distemper which the men underwent also.
4. But when Pharaoh did not even then yield to the will of God, but, while he gave leave to the husbands to take their wives with them, yet insisted that the children should be left behind, God presently resolved to punish his wickedness with several sorts of calamities, and those worse than the foregoing, which yet had so generally afflicted them; for their bodies had terrible boils, breaking forth with blains, while they were already inwardly consumed; and a great part of the Egyptians perished in this manner. But when the king was not brought to reason by this plague, hail was sent down from heaven; and such hail it was, as the climate of Egypt had never suffered before, nor was it like to that which falls in other climates in winter time, (26) but was larger than that which falls in the middle of spring to those that dwell in the northern and north-western regions. This hail broke down their boughs laden with fruit. After this a tribe of locusts consumed the seed which was not hurt by the hail; so that to the Egyptians all hopes of the future fruits of the ground were entirely lost.
5. One would think the forementioned calamities might have been sufficient for one that was only foolish, without wickedness, to make him wise, and to make him Sensible what was for his advantage. But Pharaoh, led not so much by his folly as by his wickedness, even when he saw the cause of his miseries, he still contested with God, and willfully deserted the cause of virtue; so he bid Moses take the Hebrews away, with their wives and children, to leave their cattle behind, since their own cattle were destroyed. But when Moses said that what he desired was unjust, since they were obliged to offer sacrifices to God of those cattle, and the time being prolonged on this account, a thick darkness, without the least light, spread itself over the Egyptians, whereby their sight being obstructed, and their breathing hindered by the thickness of the air, they died miserably, and under a terror lest they should be swallowed up by the dark cloud. Besides this, when the darkness, after three days and as many nights, was dissipated, and when Pharaoh did not still repent and let the Hebrews go, Moses came to him and said, "How long wilt thou be disobedient to the command of God? for he enjoins thee to let the Hebrews go; nor is there any other way of being freed from the calamities are under, unless you do so." But the king angry at what he said, and threatened to cut off his head if he came any more to trouble him these matters. Hereupon Moses said he not speak to him any more about them, for he himself, together with the principal men among the Egyptians, should desire the Hebrews away. So when Moses had said this, he his way.
6. But when God had signified, that with one plague he would compel the Egyptians to let Hebrews go, he commanded Moses to tell the people that they should have a sacrifice ready, and they should prepare themselves on the tenth day of the month Xanthicus, against the fourteenth, (which month is called by the Egyptians Pharmuth, Nisan by the Hebrews; but the Macedonians call it Xanthicus,) and that he should carry the Hebrews with all they had. Accordingly, he having got the Hebrews ready for their departure, and having sorted the people into tribes, he kept them together in one place: but when the fourteenth day was come, and all were ready to depart they offered the sacrifice, and purified their houses with the blood, using bunches of hyssop for that purpose; and when they had supped, they burnt the remainder of the flesh, as just ready to depart. Whence it is that we do still offer this sacrifice in like manner to this day, and call this festival Pascha which signifies the feast of the passover; because on that day God passed us over, and sent the plague upon the Egyptians; for the destruction of the first-born came upon the Egyptians that night, so that many of the Egyptians who lived near the king's palace, persuaded Pharaoh to let the Hebrews go. Accordingly he called for Moses, and bid them be gone; as supposing, that if once the Hebrews were gone out of the country, Egypt should be freed from its miseries. They also honored the Hebrews with gifts; (27) some, in order to get them to depart quickly, and others on account of their neighborhood, and the friendship they had with them.