On Passover, why is this night different from all other nights?

On all other nights, we eat leavened bread and Matzah;
on this night, we eat only Matzah.
On all other nights, we eat all kinds of herbs;
on this night, we eat mainly bitters.
On all other nights, we do not dip even once;
on this night, we dip twice.
On all other nights, we may eat sitting straight or reclining;
on this night, we all recline.

Happiness to you at Passover