In Parashat Shemini we read about the kosher and non-kosher animals. We have the fish, we have the birds, we have the animals. The Mishna tell us in Massechet Nidah that there are two kosher signs for a fish: fins and scales. But the Mishna tells us,
כל שיש בו קשקשת יש לו סנפיר
, if there are scales then there are fins – if there are scales, then you know the fins are there.
ויש בו סנפיר ואין לו קשקשת
, but there might be fins without scales.
The Gemara asks, if scales always means fins, but fins doesn’t always mean scales, then why isn’t there just one sign for a fish because if there are scales, then you know there are also fins?!
The Gemara answers cryptically,
להגדיל תורה ולהאדיר
, for the greatness of Torah. What does that mean?