Why in the Amidah do we only bow at some Boruch Atah Hashem’s, and not in all of them?
Answer:
The Sages enacted that a person bow in two of the eighteen blessings (Berachos 34). We bow in the first blessing, as if greeting the King, and in the blessing of Thanks, expressing how we owe everything, including our very existence, to Him.
Beyond this, it is considered improper, and a sign of haughtiness (Talmidei Rabeinu Yonah 24a), to bow. In addition, if we were to bow throughout the prayer, the special nature of the two blessings would be indiscernible.
Only the king of Israel has the right to bow throughout the prayer.
