Tefillah—prayer תפילה

"And to serve Him with all your heart." What service is with the heart? This is prayer, the Talmud answers. From that verse the main thing is also plain: prayer is not an appendix to sacrifice, nor a substitute for it for a while; it is called a service in its own right.

Whence three times a day. On this there is a dispute: some derive it from the patriarchs—Abraham fixed the morning prayer, Isaac the afternoon, Jacob the evening; others from the standing offerings in the Temple, of which there were two, the third prayer answering to the parts that burned through the night. The dispute is not idle: it asks whether prayer comes from man or from the Temple, and the Talmud lets both reasons stand side by side.

Why the text is one for all. While prophecy lived, each prayed in his own words. The men of the Great Assembly fixed the blessings and the prayers, and Rabban Gamliel at Yavneh settled the order—after the destruction, when the community needed something held in common. So the Amidah came to be. One may pray in any language one understands: this is stated outright.

Keva and kavanah. "Do not make your prayer fixed," says the Mishnah—that is, a duty discharged without attention. And in the same breath the order of prayer is settled to the word. There is no contradiction: the words are given so that one need not search for words, but the attention must be one's own, and no order can supply it.