"My father was fugitive Aramean. He went down to Egypt with meager numbers and sojourned there; but there he became a great and very populous nation." Rosh Hashanah is on the immediate horizon, and I am quoting from the Haggadah. Indulge me, as this well-known statement is found in Ki Tavo.
In an agrarian society, the citizenry was commanded to bring their "first fruits" to the Temple and present them to the Kohen in a declaration of gratitude to God for his eternal role in our history, with the realization that he (the farmer) dedicates everything he has to the service of God. Before doing so, the farmer recited a brief outline of Jewish history acknowledging God's obvious role. It now has a major place in the Haggadah (right after the four sons).
Initially, those who were able to recite the "First Fruits Recitation" did so while a prompter assisted those that could not. When those who required a prompter ceased coming out of humiliation, the procedure was changed so that a prompter led everyone. This is one of the rare instances of the Torah prescribing the precise words of a prayer rather than leaving it to the inspiration of the worshiper's own heart. One of the advantages of a set liturgy, in addition to uniting all Jews across barriers of time and space, is that is reminds us of themes we might not think of on our own. (Etz Hayim
In my fourth year of rabbinical school, Lauren and I were in Israel and were Jewish Life Coordinators for a group of 55 recent American high school graduates on a pre-college program. Every few weeks we would travel to foreign countries, and I was astounded time and time again that the tunes at Jewish religious services were markedly different from one country to another. However, as we went from Bulgaria to Greece to Spain to Yemenite communities in Israel, the liturgy was virtually identical. Yes, one can "pray what is in his or her heart", but it is important to adhere to the proscribed liturgy lest one forget something. (I will be speaking more about this on Rosh Hashanah.)
From the days of our forefathers there have been modest changes. The most obvious of these is the 19th blessing added to the Shemona Essray(The 18 Blessings), which we in the Conservative Movement generally refer to as the Amidah. All in all, there is no difference in the prayer format we use from that of our great, great, great grandfathers. That is the tie that binds us.
Rabbi Jeffrey Abraham