How do we know that we must take an etrog as the fruit in the
Four Kinds, and that I cannot just use a lemon or an orange? The
Torah describes the fruit which we must take as פרי עץ הדר—pri
etz hadar, which translates loosely as the “fruit of a tree
which is hadar.” What is hadar? Since the days of Moses, we have
known this to be an etrog. There was never a time when the
identity of the fruit needed was in doubt. Rather, each
generation told the next generation which fruit was needed to
complete the Four Kinds. Nevertheless, various propositions were
made to demonstrate that this can also be understood from the
text. The common meaning of הדר hadar is “beautiful.” Ibn Ezra
writes that the etrog is known as the most beautiful of all
fruits, and when the Torah tells us to take a beautiful fruit,
the only possible candidate is the etrog. Alternatively,
Nachmanides writes that hadar is actually the ancient Hebrew
name for the etrog, the latter being its Aramaic name. Hence the
verse is simply telling us to take t