The ultimate purpose of the ten plagues was: "In order that you should tell your son and grandson. . . " For if the purpose of the plagues was simply in order that Pharoah should let free B'nei Yisroel, HaShem could have immediately brought number ten, the slaying of the first born, and Pharoah would have conceded. Thus the main reason behind the makos was in order that the children of Israel should see HaShem's guiding hand and as a result be strengthened in their emunah; them and their children after them. That is why there were ten different makos, for each individual of klal yisroel was affected by a different one. To one person the plague of blood might have made an impression. While his neighbor wasn't influenced so much from the maka of blood, but rather that of arov, for example. In all of Egypt there were wild animals. But not one entered the land of Goshen. From where did the animals know where Goshen was? Which school did they go to that taught them to read the sign saying: "Welcome to Goshen"?? In each and every maka they saw HaShem and thus attained Yiras Shomayim.
The Ramchal said: "If the knowledge of G-d was clear to us, we wouldn't sin." Every sin therefore comes from a lack of belief in HaShem. Someone who has 100% total emunah will never come to sin.
The Midrash relates to us that when Moshe Rabeinu was growing up in Pharoah's house he one day, as a child, removed Pharoah's crown from his head. His advisors told him that this was a sign that Moshe was to be the savior of the Jews. However, others claimed that since Moshe was still an infant he was too young to be responsible for his actions. So they put him to the test: they brought him two bowls. One of gold and silver and one of hot coals. Moshe wanted to take the gold and silver but an angel came and pushed his hand over to the coals . . . by way of "drash" one could explain the Midrash as follows: The evil inclination was telling Moshe to take the gold and silver as opposed to sticking his hand in fire. However, the angel, the Yetzer Hatov, told Moshe that in fact the gold and silver is a "fire" which is even more dangerous than burning hot coals. For they can bring a person to sin which is even a stronger "fire"!
The Gemorah says that if a person finds shatnez in his clothing he should remove it even in the middle of the market place. The question is asked: How can it be expected of a person to bring upon himself such a terrible embaressment? The answer is quite simple: If someone was in the midst of a crowd of people and he noticed suddenly that his clothes caught on fire, would he leave his clothes on to avoid embaressment? Certainly not. Chazal knew and felt that each sin is "fire" to a person. As such, if he is wearing shatnez, i.e.: his clothes are burning, so to speak, he must remove them immediately, even in the market place!
Chag Kasher V'sameach