daf bit: Nazir 54
The talmud discusses a variety of sources of ritual impurity and how they
affect a nazir. One such source, listed in a mishna on today's daf,
is "the land of the gentiles" -- one who has taken a wow to be a nazir
is apparently expected to stay within the land of Israel for the duration.
The g'mara then analyzes this case more closely, asking what exactly it is
about gentile lands that causes impurity. Some say it is breathing the air,
while others say it is contact with the soil. The g'mara here is a
little confusing, but it appears to conclude that the impurity comes from
the soil. (54a-b)