Bo

Hashem said to Moshe, "Come to Par'oh,
for I have made his heart and the heart of his servants stubborn
so that I shall place these signs of mine in his midst.
And so that you may relate in the ears of your son
and your son's son that I have amused myself with Egypt,
and my signs that I placed among them -
that you may know that I am Hashem.

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Shmot 10:1-2 (Opening lines of Parshat Bo.)

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These lines are the introduction to Arbeh, the plague of locusts. This is the last plague that hit the landscape of Egypt. After this calamity Paroh's question, "Who is Hashem that I should listen to His voice?” was definitively answered. In the aftermath of this devastation the locusts retreated on their own volition, because there wasn't anything left for them to ravage. Paroh, left with nothing and unable to feign strength confesses, "I have sinned to Hashem."
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Rav Simcha Zissel Broide noted that the point of the decimation was not merely to get Par'oh to acquiesce and release the Jews. The goal was to show Paroh who G-d is. Right before Arbeh Hashem states that part of the agenda is to pass on to future generations the story of what G-d did to Egypt, so that they will know who He is.
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Rav Yaakov Weinberg takes the reference to ears as a metaphor for speech that is heard only superficially by ears but does not reach the heart. In other words, we should tell young children about these miracles despite the fact that they can't really comprehend. This is why we teach kids the fundamental statements "Torah tziva lanu Moshe…" and "Shma Yisrael". Words that enter ears but not hearts still make an impression. And there remains the possibility that greater understanding will follow at a later time.
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This relates to the Kotzker Rebbe's comment on a line that we recite daily in Shma. Words of Torah are described as placed upon our hearts. The Kotzker Rebbe explained that words aren't always taken inside a person's heart. Once stated, words rest atop the heart and when the heart opens they will be there to go in. This is why children were taken to the Beit HaMikdash for the Torah reading of Hakhel. This also explains why a day school education is so important even if it seems ineffective.
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This approach may help with my childhood friend Scott's haunting lament that Yeshiva taught him Gemora and Chumash and Tefila but not love of Torah. Perhaps the answer is that the best anyone can do for anyone else is put words in ears or on hearts. The absorption of the truth and goodness of Torah is a private process and a personal responsibility.
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Rav Yaakov noticed that the pasuk ends by stating that the result of teaching our children is that we, not they, will know what we taught. As Rav Yisrael Salanter said, "It's worth speaking the truth even if only one person gets the message, and even if that one person is the speaker."