The Rambam's Eleventh Principle: Parts of a Mitzvah are not Individual Mitzvos

Some mitzvos are made up of parts, like waving the four species on Succos. Waving all four species – lulav, esrog, hadassim and aravos - is a single mitzvah, not four mitzvos. Similarly, the Torah commands that six things be gathered for the purification process of the metzora (popularly translated as “leper,” but not really). These six things – two birds, scarlet, hyssop, cedar, spring water and a clay pot – are collectively ONE mitzvah.

The Rambam discusses the Talmudic principle of two things being mutually indispensable – that is, a mitzvah simply cannot be fulfilled if you’re missing one of them (like a lulav or an esrog). He cites the Talmud in Menachos 27a, where a number of examples are provided. (Most of them have to do with sacrifices and the Temple service.) Anything that has such interdependent components is clearly a single mitzvah. No lulav? Waving the other three species is pointless. No hyssop? The metzora can’t be purified.

The real difficulty occurs when parts of a mitzvah are not mutually indispensible. For example, tzitzis were originally meant to have a blue thread made of a particular dye, now generally accepted as lost. The Talmud in Menachos 38a tells us that the blue thread and the white threads are not mutually indispensible. One might think that they are therefore two separate mitzvos, but the Rambam cites a statement in the Mechilta that tzitzis is still a single mitzvah, since Numbers 15:39 says that “it” (singular) will be tzitzis – that is, a single mitzvah.

So one mitzvah can have many components. If the parts are mutually indispensible, it’s clearly a single mitzvah. But even if the mitzvah can be fulfilled missing a part (like most of us today wear tzitzis without the blue thread), it might still be a single mitzvah! What matters is not the number of pieces, but the end goal of the mitzvah.