Regarding a “clean body” (Heb. ‘guf naki’):
As mentioned, if a person cannot avoid passing gas or is constantly running to the bathroom, he is categorically exempt from the mitzvah of tefillin. It does not matter whether he feels discomfort or pain, or is pain-free, for pain is not the basis for his exemption, rather it is his lack of a clean body. (Note: A person in this state is not permitted to wear his tefillin even if he wanted to, as this would be disrespectful! If a person is in pain for whatever reason – even if his body is totally clean from a G.O. standpoint - he is also exempt; however, it is his prerogative to be “strict” and wear them in spite of his pain, provided that his body is clean]
Question: What if a person can control his body for a short while, but not long enough to daven the entire davening?
Answer: Remember: the inability to control one’s body from passing gas is not only an obstacle to wearing tefillin – it also compromises one’s worthiness of davening altogether. Here are some options, from best case scenario to worst:
1) Wear the tefillin during the recitation of Krias Shema and Shemoneh Esrei. If that is not possible, 2) Wear them for the recitation of Krias Shema, but do not attempt to daven the Shemoneh Esrei at all - even without tefillin on - because passing gas while one is “standing before the King” is not appropriate either. If that is not possible,
3) Do not attempt to wear tefillin even during the Krias Shema. He may recite the Krias Shema, and if and when he must pas gas, he should stop his recitation and wait until the odor dissipates. (Note: He should attempt to put on his tefillin for a short while at any time during the day, as we have learned.)
If a person is uncertain whether or not he can control his body, he should attempt to wear tefillin and daven – even with a minyan - and try as best as he can to control himself.
Regarding a “clean mind”:
One who finds it difficult to refrain from unclean thoughts is sooner urged to try mightily to control himself – by filling his thoughts with Yiras Shamayim (fear of Heaven) etc. – than to claim exemption as one who cannot maintain a clean body. This is because one’s thoughts are more under his jurisdiction than his bodily functions. (Ed: While surely it can be difficult to control our thoughts sometimes, think about all those mitzvos which command us to control our thoughts, such as “Love your fellow Jew as yourself”, “Do not covet”, “Do not hate your brother in your heart”, just to name a few…)
Question: Are women obligated in the mitzvah of tefillin? If not, are they permitted to wear them, as with other mitzvos from which they are exempt?
Answer: Women are exempt from tefillin, just as they are exempt from most time-bound positive mitzvos. (Note: Tefillin are time-bound by their exemption on Shabbos and Yom Tov – not by their exemption at night, which is only rabbinic.) However, unlike others, because of the unique requirement of maintaining a clean mind and body while wearing tefillin, women are strongly discouraged by halacha from wearing them on a voluntary basis.