13:
The second item in the triad attributed to Rabbi Shim'on ben-Netan'el is that we not make our prayer "fixed". There are two Hebrew words here that need to be elucidated before we can evaluate this teaching.
14:
Firstly, the word 'prayer'. While this word does have a general connotation in the language of the sages more often than not it is intended to indicate what we now call the Amidah. This is the basic prayer-element of our liturgy. Its name derives from the fact that this act of worship is recited while standing. (It is also called Shemonah-Esreh [the 'eighteen'] because the weekday version of the Amidah originally consisted of 18 short petitions each concluding with an appropriate benediction. Nowadays there are 19.) Thus the probable intention of Rabbi Shim'on is to warn us not to make the recitation of the Amidah "fixed".
15:
The other word which requires elucidation is "fixed". When we last encountered this word was in Avot 1:15 where Shammai told us to "make your Torah fixed". There we understood him to be telling us to set aside regular times for study of Torah. It does not seem very likely that Rabbi Shim'on intended to tell us not to set aside regular times for reciting the Amidah! Like the Shema, the Amidah too is to be recited within certain clearly defined time periods. There are two other possible meanings that can be suggested. It is possible that Rabbi Shim'on is asking us not to use a fixed text for our Amidah, but rather to let the words flow freely as prayerful supplication of God's mercy where the loving heart innovates new texts each time.
16:
While this interpretation is in direct contradiction to our modern custom of reciting our prayers in an unchanging format from a printed text, in earlier times the situation was different. When they formulated the Amidah the sages did not create a fixed text but a fixed framework. They defined the subject-matter of each of the benedictions and also the exact wording (more or less) of each concluding benediction. But the actual words recited by each worshipper were supplied by the worshipper himself. Of course, there must have been many people - perhaps the majority - who were not able to formulate innovative wording to a pre-defined subject three times a day. Indeed, just like today, surely the majority of people would not have been able to 'ad lib' their prayers even once daily. This was one of the reasons why the rôle of the Prayer-Leader was introduced: people who were not capable of reciting their prayers in this manner could listen to the prayer said out loud by the Prayer-Leader [Sheli'aĥ Tzibbur] and, by responding 'Amen' to his benedictions could thus be deemed to have fulfilled their duty.
17:
If this is the meaning of the teaching here if Rabbi Shim'on he must be addressing himself to the select minority of people who were capable of making the content of their daily worship meaningfully innovative. As we shall see, the sages addressed this problem in several different ways.
To be continued.