The gemara (Talmud) in Yuma (35b) states in an interesting bereita (addendum): ani v'ashir v'rasha ba'in la'din. Each person, the poor man, rich man, and rasha (wicked person) are brought to judgment and asked the same question, mipnei ma lo asakta batorah, why didn't you learn Torah? Each gives their particular excuse and each of them is countered by a story about a great person who was either poor, rich, or had the potential to be a rasha, and still learned Torah or remained righteous. The gemara concludes "Hillel obligates the poor people, Rebbi Elazar Ben Charsum obligates the rich people, and Yoseph obligates the reshaim" .
Rav Henoch Lebowitz zt'l asks an incredible question on this gemara. Why is it that the gemara relies on the stories of these holy people to challenge the actions, or lack thereof, of the person on trial? Hashem knows the makings and life of every person and knows whether or not it was within their capability to learn or not. Why does Hashem need to use these examples of people who succeeded, to prove his point? Why can't he just say "I know you could have learned more and your excuses are not legitimate because I KNOW YOU"!
Besides, if the poor person was capable of learning more than he actually did, he would be liable for this regardless of whether or not there was a standard set by Hillel.
To answer this question Rav Lebowitz points towards the Daas Zekeinim miBaalei Tosofot (a commentator) in our parasha, who brings an interesting narrative about Avraham Avinu (Abraham the Patriarch):
When Hashem commanded Avraham to circumcise all the people of his house, kol anshei beito, Avraham went to Aneir and Eshkol to ask what he should do with the people of his house who do not want to be circumcised. They did not know what to answer him. Avraham then went to Mamrei and they advised him to first circumcise himself and his son, Yishmael, and when they see this they will agree to be circumcised as well. Avraham followed their advice as the pasuk (verse) states "on that day Avraham and his son were circumcised", and afterwards vechol anshei beito nimolo ito, all the people of his house were circumcised with him.
Rav Lebowitz points out that it may at first seem strange for Avraham to do this. After all, after he becomes circumcised he will not have the strength to inspire the others to go through with the bris. Thus we learn an important lesson: when one wants to impress upon others to be or act a certain way, they must model that way of being and be a living example of that which they wish to impart. Only by going through with the bris himself was Avraham able to get anshei beito, his household, to go through with it as well.
This, says Rav Lebowitz clarifies our gemara. He explains that it was necessary for the stories of these great people to be mentioned because without them, the poor, rich, and unrighteous would never know how to live their lives with Torah. If the best way to impart a message to someone is to set an example, then there must be an example for these people to have learned from. The poor man truly has no excuse to have not learned Torah since he was not only commanded by God to learn, but also had Hillel as a living example of what was possible for a man of his stature. Without these living examples God truly could not have fairly prosecuted these perpetrators.
We learn from this a very important lesson in chinuch (education) and in life. Giving fiery mussar (exhortation) will have minimal effects. In order to impart certain values and beliefs to those who look up to us, we must live those values and beliefs. This applies to our children, our students, and to those around us.
If we truly want to make the world a better place, we must "be the change [we] want to see in the world." By doing this others can follow by example and we can create the ideal world, a world that is ready for the coming of Moshiach, may it be speedily in our days.