You see that when man separates from a settled area, he finds himself
detached from his "place," He is then deprived of the special protection
provided him, according to the order of the world as created by G-d. This
is why a place is called "makom," (from the same root as "kiyum," which
means survival or existence) for is one's existence is dependent upon and
provided by a suitable environment.
When man departs from a place which is inhabited, he finds himself out of
his "makom." It is the "makom" which provides natural protection for his
existence, and being out of that place deprives him of that system of
Furthermore, man is protected when he is within a "klal" (a unified
community). Even if man is alone in his home (seemingly not part of the
klal at that moment) being in a city with many other people includes man
within the system of protection afforded to a community.
Therefore, the Mishna teaches specifically about a person walking ALONE on
the ROADWAY. He has left the protective system of this natural place (by
being on the road). And he has isolated himself (albeit temporarily) from
all other people (by being alone).
(The word "derech" means a main roadway connecting two different places,
rather than a local street.)
There is a mystical concept about the protection accorded two people
together (as opposed to one person by himself) as seen in the following
lesson (Berachoth 43b): To one person, [the demon] appears and causes harm;
to two people it appears, but doesn't cause harm; to three people it doesn't
Man, created "b'tzelem Elokim," as a reflection of the Divine, is worthy of
being above all other creatures, as we are taught (Shabbath 151b, Sanhedrin
38b): No animal can have control over man unless man becomes like an beast,
as it is written (Tehillim 49:21) "Nimshal k'beheimoth nidmu. (One who is
ruled over, is compared to a beast.)
(This is an example of the Rabbis departing from the contextual and literal
translation of the verse to extract an ethical lesson. One studying the
verse sees that its literal translation is "[Man without understanding] is
compared ("nimshal") to silenced ("nidmu") animals (beheimoth)" However, the
word "nimshal," also means "be ruled over," the passive form of the root
"limshol." The word "nidmu" also means "compared to," from the root "domeh,"
meaning "similar." These kinds of Rabbinic interpretations aren't simply
poetic license, but reflect an understanding that connects the contextual,
literal translation with the deeper, modified understanding of the text.
(The Maharal explains a number of times that the word "drash," which we
usually associate with an interpretation that ignores the literal meaning of
the text to create some kind of forced "word association," in fact comes
from the word "demand, or "thorough inquiry." See Devarim 13:15 and Rashi.
Also Devarim 19:18. The drasha is the meaning of the text as it demands to
be understood if one probes the text thoroughly and deeply enough to reach
its true meaning. See Be'er HaGolah, the beginning of Be'er III, pg. 44 in
the Hoenig edition and page 220 in the Hartman edition. See also this
section in the English translation of Be'er HaGolah by Rabbi Yitzchok