אמר רבי אבא בר כהנא גדולה הסרת טבעת יותר מארבעים ושמונה נביאים ושבע נביאות שנתנבאו להן לישראל שכולן לא החזירום למוטב ואילו הסרת טבעת החזירתן למוטב
This is one of my favourite shtikles. I usually just link back to the original but in this case I'll reinsert instead:
At first glance, this passage seems to be delivering a very simple message. Actions speak louder than words. בני ישראל were never able to internalize the messages of the prophets and act upon them accordingly. But when they saw their imminent extermination before their very eyes, they knew there was only one answer.
But there is a grave difficulty with this approach. The rebukes of the נביאים were indeed ignored, on the whole. But the destruction of בית המקדש did not happen overnight. There were many events that led to its destruction, many steps along the way where בני ישראל ought to have taken heed more so than they did to the mere words of the prophets. So one can understand why אחשורוש's actions sent a stronger message than the rebukes of the prophets. But what about the siege on ירושלים? What about the breeching of the walls? In what way were they less inspiring than the removal of the ring.
To establish a direction on this, we must consider the מהרש"א's commentary on the above passage. He asks why the removal of the ring is singled out by the גמרא. After all, it could simply have stated that the המן's evil decree was greater than the prophets. What is the true significance of the removal of the ring? He answers that when a purchase is made between two parties, it is common for the buyer to make a deposit to ensure the seller of his commitment to the transaction. In this case, the buyer would have been המן. He was "acquiring" the king's consent and approval for his evil plan. And yet, it was אחשורו who gave his ring to המן. This gesture showed אחשורוש's true feelings towards the Jews and המן's plan. It was more content than consent, as if he was now asking המן to carry it out, not allowing it. With the supreme ruler of the inhabited world against them, the Jews realized they were doomed.
With this important point, we can suggest an approach to answer our question above. The prophets' warnings and calls for repentance leading up to the destruction of the בית המקדש were all during a time when בני ישראל were an autonomous nation in their homeland. They were facing invasion and incursion from forces from the outside. Even when נבוכדנצר was banging down the doors and ירושלים was ready to fall, this position gave them the false hope to believe that somehow they could simply beat back the invading forces. They were therefore unable to appreciate the true urgency and necessity for תשובה.
The circumstances were vastly different during the era of אסתר. They were strangers in a strange land. They didn't have their own leaders, their own army or their own land. They were fully aware that they were at the whim of their rulers. When they saw that the supreme ruler was bent on their destruction, they knew there was simply nothing they could possibly do - except תשובה!
This is, of course, a very important and prevalent lesson today. We certainly need an army as any other country does. We even need to invest in the Iron Dome and pursue the protection of our nation in every normal way. We simply cannot rely on these institutions and believe that everything will be okay because they are in place. We must understand that is השם who grants triumph to these endeavours and it is our תפלה and תשובה that fuels their continued success.
