We addressed your question in the Insights to the Daf, which you can find in our archives (http://www.dafyomi.co.il/makos/insites.htm). I include a copy here for your benefit.

Be well,

M. Kornfeld

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1) REDUCING THE NUMBER OF MITZVOS

QUESTION: The Gemara says that Moshe Rabeinu taught us the 613 Mitzvos, but later Nevi'im reduced the number. David ha'Melech narrowed them down to 11, Yeshayah made them 6, Michah made them 3, and Yeshayah then narrowed them down to 2. Finally, Chabakuk categorized all of the Mitzvos as one single Mitzvah.

What does the Gemara mean when it says that the number of Mitzvos was reduced?

ANSWERS:

(a) The RAMAH (cited by the BEIS ELOKIM (Sha'ar ha'Yesodos 35), the MAHARSHA, and HA'KOSEV in the Ein Yakov; see also RITVA) explains that we find in Sotah (21a) that the performance of Mitzvos protects a person from the Yetzer ha'Ra (see also Avos 4:2, "Mitzvah Goreres Mitzvah"). Originally, a person merited this special protection only if he fulfilled all of the Mitzvos of the Torah. However, David ha'Melech and the later Nevi'im prayed that Hash-m should have mercy even on the person who does not keep all of the Mitzvos, and give the same protection to such a person.

The CHIDA (in Pesach Einayim) adds that perhaps David ha'Melech narrowed them down to 11 Mitzvos to correspond to the 11 herbs that comprise the Ketores, which, the Gemara in Shabbos (88a) relates, has the power to repel the Mal'ach ha'Maves, who also is the Yetzer ha'Ra (Bava Basra 16a).

The IYUN YAKOV and KOS YESHU'OS add that perhaps the limited number of Mitzvos that the later Nevi'im mentioned will also protect a person from physical harm, and not only from the Yetzer ha'Ra. The Gemara in Sotah there mentions that this is also one of the effects of Mitzvah observance.

(b) The SEFER HA'IKRIM (3:30, cited by the Beis Elokim and Maharsha) and MAHARAL explain that the later Nevi'im saw that it was too difficult for a person to concentrate on 613 individual Mitzvos when fulfilling each one. They therefore placed the Mitzvos in general categories, where each category includes a large number of the Mitzvos of the Torah. In this way, it would be easier for a person to fulfill the entire Torah while concentrating only on a limited number of Mitzvos.

The Maharsha adds that in truth, all of the 613 Mitzvos are based on certain general categories, as we find that the Aseres ha'Dibros allude to all 613 Mitzvos. Moreover, all of the Mitzvos can be narrowed down to one basic Mitzvah that encompasses all of the Mitzvos -- the Mitzvah of Emunah in Hash-m. This is the intention of David ha'Melech when he says, "Kol Mitzvosecha Emunah" -- "All of your Mitzvos are Emunah" (Tehilim 119:86). The Maharsha adds that this is necessarily so, since Hash-m is One, and thus His will must be one. This is why we find that Hash-m Himself spoke to the Jewish people at Sinai and told them all of the Aseres ha'Dibros at once, and then He later began to repeat them separately so that the Jewish people could hear each one individually. This means that from Hash-m's perspective, the Mitzvos are all one; they are all the unity of Hash-m's will. However, we cannot understand all of the Mitzvos from that perspective, and therefore we need them to be spelled out individually, into 613 Mitzvos.

This is what the Gemara means when it introduces this discussion by saying that we heard the Mitzvos of "Anochi" and "Lo Yiheyeh" directly from Hash-m. These two Mitzvos are the two parts to the Mitzvah of Emunah (i.e. to accept Hash-m, and not to accept any other power), and this is the Mitzvah that we heard directly from Hash-m when He began to repeat each individual Mitzvah. It is this Mitzvah in particular that He expressed to us, because it is the Mitzvah of Emunah which encompasses all of the Mitzvos.

(See additional approach in the Beis Elokim, ibid.)