The gloom of this period of the “Three Weeks” leading up to Tisha Be’av has been brought home to us as we grieve for those who have given their lives to protect us. This has been a time of suffering and anxiety for Israel. It is well to remember that after Tisha Be’av comes Shabbat Nahamu – the Sabbath in which we are comforted, bringing with it the hope that this time too, as so many times before, adversity will be followed by better times. We Jews have a way of turning tragedy into triumph and we can only pray that this will happen once again.We should consider, for example, not only the tragedy of the destruction of Jerusalem and the exile of the Twelve Tribes to Babylon in 586 BCE, but the triumph of the survival of Jews and Judaism that followed.It was certainly not a given that they would not disappear from the world, that there would be a return to Zion and that the Jews would flourish as a people and create a religion that has survived for thousands of years.In ancient days, it was common for a conquered people to cease to exist. If carried to a foreign land, they would usually simply assimilate into that culture. The defeat of a nation and the destruction of its cultic center was often considered to be the defeat of the god of that nation by the superior gods of the conqueror.That, of course, could not be the case with Israel – for the simple reason that Israelites were convinced their God was the only God, and could not be defeated.Whatever the reason for their defeat, it was not because another god had triumphed.There were no other gods.It was this belief that kept them from assimilating into Babylonian culture and religion. On a positive note, all the prophets had predicted that the God of Israel would never abandon the people, but would bring them back. They therefore never lost hope. Nevertheless, survival in exile required them to find creative ways of sustaining their religion under new conditions, and especially in the absence of the Temple.Their leaders created important innovations that served them well. Worship without sacrifice, together with study of Israel’s ancient traditions and writings, provided a means of retaining their faith.By the time groups of exiles returned to Jerusalem, first in 538 BCE and then more substantially with Ezra in 458 BCE, some 130 years after the destruction, they brought with them important changes in Judaism that had developed and changed the religion of Israel in substantial ways – all the while retaining the core of basic beliefs that had existed previously. Among these were the institution of the synagogue as a place of verbal worship and study, the acceptance of the Torah as the divine law, the emphasis of studying that text and the emergence of scribes – sofrim – who were experts in that text and served as teachers of it.These scribes basically replaced the kohanim, whose only task now was the sacrificial ritual.All of this resulted in the democratization of Judaism, permitting anyone to become a teacher of Torah or to conduct the rituals and teach in the synagogue.These basic innovations eventuated in the kind of Judaism that has persisted until today, in one form or another.Indeed, during the period of the Second Temple several competing forms emerged, including the Pharisaic version, that of the Sadducees and the Essenes, and many others such as the Dead Sea Sect. Each one, of course, claimed to be the real Judaism. Somehow they managed to live together inside the great tent of “Judaism.” The idea that nothing has ever changed in Judaism and that “there is today, as always, only one Judaism, the original one,” as was recently stated by the leader of Agudath Israel in America, ignores the fact that Judaism has undergone many significant changes over the centuries, and that change and diversity have always been a part of Judaism.Those who believe that their Judaism is the only authentic one, because it has never changed, are deluding themselves.A Judaism that never changes would be little more than a fossil, and fortunately that is not the case.Were it not so, we would have no synagogues, no rabbis and no yeshivot, to say nothing of such works as the Mishna, Talmud and later codes, and of the Zohar and the entire hassidic movement.Our Judaism today is an outgrowth of the ancient, original teachings going back to Moses’s adaptation of the ancient beliefs of the early patriarchs, but it is not identical.The balance between tradition and change has always been a delicate one, but also a necessary one. Our ancestors were fortunate to have been able to take the steps needed to survive in new conditions and to triumph over adversity. Let us hope that we too will be able to do the same. The writer, former president of the International Rabbinical Assembly, is a two-time winner of the National Book Award. His latest book is The Torah Revolution (Jewish Lights).